An isolated use was by Ebenezer Burgess in his translation of the Surya Siddhanta wherein he stated that the beginning of the Kali Yuga era occurred at midnight at the meridian of Ujjain at the end of the ,th day and the beginning of the ,th day civil reckoning of the Julian Period, or between February 17 and 18 JP or BC. He greatly expanded his usage of Julian days in his Kalendariographische und Chronologische Tafeln containing over , Julian days, one for the zeroth day of every month over thousands of years in many calendars.

He included over 25, negative Julian days, given in a positive form by adding 10,, to each. He called them "day of the Julian Period", "Julian day", or simply "day" in his discussion, but no name was used in the tables.

The Julian day number can be calculated using the following formulas integer division rounding towards zero is used exclusively, that is, positive values are rounded down and negative values are rounded up : [f]. The months January to December are numbered 1 to JDN is the Julian Day Number. Use the previous day of the month if trying to find the JDN of an instant before midday UT.

Divisions are integer divisions towards zero ; fractional parts are ignored. Divisions are integer divisions, fractional parts are ignored. For the full Julian Date of a moment after UT one can use the following.

Divisions are real numbers. For a point in time in a given Julian day after midnight UT and before UT, add 1 or use the JDN of the next afternoon. The US day of the week W1 for an afternoon or evening UT can be determined from the Julian Day Number J with the expression:.

If the moment in time is after midnight UT and before UT , then one is already in the next day of the week. The ISO day of the week W0 can be determined from the Julian Day Number J with the expression:. This is an algorithm by Edward Graham Richards to convert a Julian Day Number, J , to a date in the Gregorian calendar proleptic, when applicable.

Richards states the algorithm is valid for Julian day numbers greater than or equal to 0. D , M , and Y are the numbers of the day, month, and year respectively for the afternoon at the beginning of the given Julian day. Let Y be the year BC or AD and i, m and s respectively its positions in the indiction, Metonic and solar cycles. As stated above, the Julian date JD of any instant is the Julian day number for the preceding noon in Universal Time plus the fraction of the day since that instant.

Ordinarily calculating the fractional portion of the JD is straightforward; the number of seconds that have elapsed in the day divided by the number of seconds in a day, 86, But if the UTC timescale is being used, a day containing a positive leap second contains 86, seconds or in the unlikely event of a negative leap second, 86, seconds.

One authoritative source, the Standards of Fundamental Astronomy SOFA , deals with this issue by treating days containing a leap second as having a different length 86, or 86, seconds, as required. SOFA refers to the result of such a calculation as "quasi-JD". From Wikipedia, the free encyclopedia.

Days since the beginning of the Julian Period. For dates in the Julian calendar, see Julian calendar. For numbered day of year, see Ordinal date. For the comic book character Julian Gregory Day, see Calendar Man. For the artist and composer, see Julian Day artist. Not to be confused with Julian year astronomy. Julian year calendar 5th millennium BC Barycentric Julian Date Dual dating Decimal time Epoch astronomy Epoch reference date Era J — the epoch that starts on JD Astronomical calculations generally include a year 0, so these dates should be adjusted accordingly i.

In this article, dates before 15 October are in the possibly proleptic Julian calendar and dates on or after 15 October are in the Gregorian calendar, unless otherwise labelled. Conventions vary as to whether this is based on UT or local time. However, for the first measurement, the Earth is between the Sun and the targeted object, and for the second, the Earth is on the opposite side of the Sun from that object.

Then, the two measurements would differ by about light-seconds: For the first measurement, the Earth is roughly light seconds closer to the target than the Sun, and roughly light seconds further from the target astronomical object than the Sun for the second measure.

To clarify this issue, the ordinary Julian day is sometimes referred to as the Geocentric Julian Day GJD in order to distinguish it from HJD.

That paper gives algorithms in Fortran. The Fortran computer language performs integer division by truncating, which is functionally equivalent to rounding toward zero.

B4, which states is year of the Julian Period. Julian date. Various timescales may be used with Julian date, such as Terrestrial Time TT or Universal Time UT ; in precise work the timescale should be specified. Ticks documentation". Retrieved January 14, Digital Equipment Corporation -Customer Support Center. Colorado Springs. June 6, Archived from the original on June 6, The Python Standard Library.

In he used " Iulianam vocauimus: quia ad annum Iulianum duntaxat accomodata est " on p. The Christian day was current, not elapsed. Doggett, Ch. Alsted, Johann Heinrich []. Encyclopaedia in Latin , Tome 4 , Page American Ephemeris and Nautical Almanac, Washington, —, Hathi Trust Astronomical almanac for the year Nautical Almanac Office and Her Majesty's Nautical Almanac Office. ISBN Astronomical almanac for the year Naval Observatory and Her Majesty's Nautical Almanac Office.

Astronomical Almanac Online. Bede: The Reckoning of Time , tr. Also Appendix 2 Beda Venerabilis' Paschal table. Blackburn, Bonnie; Holford-Strevens, Leofranc.

Burgess, Ebenezer, translator. Translation of the Surya Siddhanta. Journal of the American Oriental Society 6 — —, p. Berliner astronomisches Jahrbuch, Berlin, —, Hathi Trust Chi, A. December Retrieved from NASA Technical Reports Server April 24, Collins, John — Connaissance des Temps —, Hathi Trust table of contents at end of book Chronicon Paschale — AD , tr.

Michael Whitby, Mary Whitby, , p. Computer Science Department, University of Texas at San Antonio. IBM Knowledge Center. Retrieved September 28, de Billy — Leo Depuydt, "AD as the first indiction cycle", The bulletin of the American Society of Papyrologists , 24 , — Dershowitz, N.

Calendrical Calculations 3rd ed. Cambridge University Press. Franz Diekamp, "Der Mönch und Presbyter Georgios, ein unbekannter Schriftsteller des 7. Jahrhunderts" , Byzantinische Zeitschrift 9 14—51 in German and Greek.

Digital Equipment Corporation. Modified Julian Day explanation Dionysius Exiguus, [], Cyclus Decemnovennalis Dionysii , Patrologia Latina vol. Dionysius Exiguus, [], tr. Michael Deckers, Nineteen year cycle of Dionysius , Argumentum 5 in Latin and English.

Explanatory Supplement to the Astronomical Ephemeris and the American Ephemeris and Nautical Almanac , Her Majesty's Stationery Office, , pp. Fliegel, Henry F. October Communications of the Association for Computing Machinery Vol.

Furness, Caroline Ellen An introduction to the study of variable stars. Boston: Houghton-Mifflin. Vassar Semi-Centennial Series.

Gauss, Carl Frederich Clarke, Arthur A. Disquisitiones Arithmeticae. Article Yale University Press. in English Gauss, Carl Frederich in Latin Grafton, Anthony T. JSTOR Grafton, Anthony T. Volume II: Historical Chronology Oxford-Warburg Studies. Venance Grumel , La chronologie , , 31—55 in French. Heath, B. Astronomia accurata; or the royal astronomer and navigator. London: author. Herschel, John F. Herschel's words remained the same in all editions, even while the page varied. Hopkins, Jeffrey L.

Using Commercial Amateur Astronomical Spectrographs , p. April 4, Ideler, Ludwig. Handbuch der mathematischen und technischen Chronologie , vol. IBM COBOL for AIX 2. Information Bulletin No. January International Astronomical Union. Defit's Definitions of Information Technology Terms.

Julian Date Converter March 20, US Naval Observatory. Retrieved September 16, Kempler, Steve. Day of Year Calendar. Goddard Earth Sciences Data and Information Services Center. Laplace Traité de Mécanique Céleste vol. Seidelmann, eds. Explanatory Supplement to the Astronomical Almanac , 3rd ed. Mill Valley, Calif. ISBN Meeus Jean. Astronomical Algorithms , 2nd ed, ISBN Mosshammer, Alden A. A little less than lunar distances make up an astronomical unit.

The siriometer is an obsolete astronomical measure equal to one million astronomical units , i. The name probably derives from early neutron-deflection experiments, when the uranium nucleus was described, and the phrases "big as a barn" and "hit a barn door" were used. Barn are typically used for cross sections in nuclear and particle physics. Additional units include the microbarn or "outhouse" [11] and the yoctobarn or "shed".

One brass is exactly square feet 9. It is also equal, however, to cubic feet 2. This unit is prevalent in the construction industry in India. The square is an Imperial unit of area that is used in the construction industry in North America, [16] and was historically used in Australia by real estate agents.

One square is equal to square feet 9. A roof 's area may be calculated in square feet, then converted to squares. In Ireland, before the 19th century, a "cow's grass" was a measurement used by farmers to indicate the size of their fields.

A cow's grass was equal to the amount of land that could produce enough grass to support a cow. A football pitch , or field, can be used as a man-in-the-street unit of area. An American football field , including both end zones, is by ft A Canadian football field is 65 yards 59 m wide and yards m long with end zones adding a combined 40 yards 37 m to the length, making it 87, square feet 8, m 2 or 0. An Australian rules football field may be approximately metres yd or more long goal to goal and metres yd or more wide, although the field's elliptical nature reduces its area to a certain extent.

A bymetre by yd football field has an area of approximately 15, m 2 1. A morgen "morning" in Dutch and German was approximately the amount of land tillable by one man behind an ox in the morning hours of a day. The area of a familiar country, state or city is often used as a unit of measure, especially in journalism. Equal to 20, km 2 8, sq mi , the country of Wales is used in phrases such as "an area the size of Wales" [25] or "twice the area of Wales". Ireland is four times as large as Wales, and France is about twenty-five times larger.

The British comedy show The Eleven O'Clock Show parodied the use of this measurement, by introducing a news article about an earthquake in Wales, stating that an area the size of Wales was affected. The Radio 4 programme More or Less introduced the idea of "kilowales" — an area 1, times the size of Wales.

The Register introduced the nanowales The measurement has been adopted by rainforest conservation charity Size of Wales , aiming to conserve an area of rainforest equating to the area of Wales. On 1 March , the charity announced that they had succeeded [29] in conserving an area of rainforest the size of Wales and will continue to operate to sustain and increase the protected area.

In the United States, the area of the smallest state, Rhode Island 1, sq mi or 4, km 2 ; the largest of the contiguous 48 states, Texas , sq mi or , km 2 ; and less commonly Alaska , sq mi or 1,, km 2 , the largest of all 50 states, are used in a similar fashion.

For example, Antarctica 's Larsen B ice shelf was approximately the size of Rhode Island until it broke up in Other areas may be described like this, too, like in the movie The China Syndrome when radiation is expected to contaminate "an area the size of Pennsylvania ". The US Central Intelligence Agency uses Washington, D.

In the Netherlands, its smallest province, Utrecht 1, km 2 or sq mi , is often used as a comparison for regions in general. The country of Belgium 30, km 2 or 11, sq mi has also often been used when comparing areas, to the point where it has been regarded as a meme [31] and where there is a website dedicated to notable areas which have been compared to that of Belgium.

The Isle of Wight km 2 or sq mi , an island off the south coast of mainland England , is commonly used to define smaller areas. It has sometimes been used in attempts to examine whether a certain amount of a given object or group would fit in a space its size; in , it was estimated that approximately 2.

In Denmark , the island of Bornholm km 2 or sq mi is often used to describe the size of an area. In Germany, the Saarland 2, In Brazil , it is common to compare relatively small areas to the state of Sergipe 21, Smaller areas are sometimes compared to the cities of São Paulo 1, A metric ounce is an approximation of the imperial ounce, US dry ounce, or US fluid ounce. These three customary units vary.

However, the metric ounce is usually taken as 25 or 30 ml when volume is being measured, or grams when mass is being measured. The US Food and Drug Administration FDA defines the "food labeling ounce" as 30 ml, slightly larger than the Several Dutch units of measurement have been replaced with informal metric equivalents, including the ons or ounce.

The shot is a liquid volume measure that varies from country to country and state to state depending on legislation. It is routinely used for measuring strong liquor or spirits when the amount served and consumed is smaller than the more common measures of alcoholic "drink" and "pint". There is a legally defined maximum size of a serving in some jurisdictions.

The size of a "single" shot is 20—60 ml 0. The smaller "pony" shot is 20—30 ml 0. According to Encyclopædia Britannica Almanac , a pony is 0. fluid ounce. In the UK, spirits are sold in shots of either 25 ml approximating the old fluid ounce or 35 ml. A board foot is a United States and Canadian unit of approximate volume, used for lumber.

It is equivalent to 1 inch × 1 foot × 1 foot cu in or 2, cm 3. It is also found in the unit of density pounds per board foot. In Australia and New Zealand the terms super foot or superficial foot were formerly used for this unit. The exact volume of wood specified is variable and depends on the type of lumber. For planed lumber the dimensions used to calculate board feet are nominal dimensions , which are larger than the actual size of the planed boards. See Dimensional lumber for more information on this.

A system of measure for timber in the round standing or felled , now largely superseded by the metric system except in measuring hardwoods in certain countries. Its purpose is to estimate the value of sawn timber in a log, by measuring the unsawn log and allowing for wastage in the mill.

This translates to a hoppus foot being equal to 1. The hoppus board foot, when milled, yields about one board foot. The volume yielded by the quarter-girth formula is A cubic ton is an antiquated measure of volume, varying based on the commodity from about 16 to 45 cu ft 0.

It is now only used for lumber, for which one cubic ton is equivalent to 40 cu ft 1. The cord is a unit of measure of dry volume used in Canada and the United States to measure firewood and pulpwood. A cord is the amount of wood that, when "ranked and well stowed" arranged so pieces are aligned, parallel, touching and compact , occupies a volume of cubic feet 3.

A more unusual measurement for firewood is the "rick" or face cord. It is stacked 16 inches The twenty-foot equivalent unit is the volume of the smallest standard shipping container. It is equivalent to 1, cubic feet 39 m 3. Larger intermodal containers are commonly described in multiples of TEU, as are container ship capacities. An acre-foot is a unit of volume commonly used in the United States in reference to large-scale water resources, such as reservoirs, aqueducts, canals, sewer flow capacity, irrigation water [42] and river flows.

It is defined by the volume of one acre of surface area to a depth of one foot. Double-decker bus. The approximate volume of a double-decker bus , abbreviated to DDB, has been used informally to describe the size of hole created by a major sewer collapse.

For example, a report might refer to "a 4 DDB hole". Olympic-size swimming pool. For larger volumes of liquid, one measure commonly used in the media in many countries is the Olympic-size swimming pool. The US National Institute of Standards and Technology NIST defines the Olympic swimming pool as 1 million litres, which is the approximate volume of the smaller FR2 pool.

Royal Albert Hall. The Royal Albert Hall , a large concert hall, is sometimes used as a unit of volume in the UK, for example when referring to volumes of rubbish placed in landfill. Melbourne Cricket Ground. A common measure of volume in Australia , and in the state of Victoria in particular, is the Melbourne Cricket Ground , the largest stadium in Australia and 13th largest in the world.

Sydney Harbour. A unit of volume used in Australia for water. One Sydney Harbour is the amount of water in Sydney Harbour : approximately gigalitres ,, cubic metres, or 0.

The Grand Canyon. With a volume measure approximately 4 orders of magnitude greater than Sydney Harbour, the volume of the Grand Canyon may be used to visualize even larger things, like the magma chamber underneath Yellowstone [54] and other things. The volume of water which flows in one unit of time through an orifice of one square inch area. The size of the unit varies from one place to another.

Here, eV electronvolt is a unit of energy the kinetic energy of an electron accelerated over one volt , 1. This definition is useful for a linear particle accelerator when accelerating electrons. The mass of an old bag of cement was one hundredweight ~ lb, approximately 50 kg. The amount of material that, say, an aircraft could carry into the air is often visualised as the number of bags of cement that it could lift.

In the concrete and petroleum industry, however, a bag of cement is defined as 94 pounds ~ In , the French term " grave " from "gravity" was suggested as the base unit of mass for the metric system. In , however, the name " kilogramme " was adopted instead. In case of planet orbiting a star, M total can be approximated to mean the mass of the central object. More specifically in the case of Sun and Earth the numbers reduce to M total ~ 1, a ~ 1 and T ~ 1.

George Gamow discussed measurements of time such as the "light-mile" and "light-foot", the time taken for light to travel the specified unit distance, defined by "reversing the procedure" used in defining a light-year.

In nuclear engineering and astrophysics contexts, the shake is sometimes used as a conveniently short period of time.

In computing , the jiffy is the duration of one tick of the system timer interrupt. Typically, this time is 0. the field rate on NTSC video hardware and the period of AC electric power in North America. One unit derived from the FFF system of units is the microfortnight, one millionth of the fundamental time unit of FFF, which equals 1. The sidereal day is based on the Earth's rotation rate relative to fixed stars, rather than the Sun.

A sidereal day is approximately 23 hours, 56 minutes, 4. The measurement of time is unique in SI in that while the second is the base unit, and measurements of time smaller than a second use prefixed units smaller than a second e.

microsecond, nanosecond, etc. SI allows for the use of larger prefixed units based on the second, a system known as metric time , but this is seldom used, since the number of seconds in a day 86, or, in rare cases, 86, negate one of the metric system's primary advantages: easy conversion by multiplying or dividing by powers of ten. There have been numerous proposals and usage of decimal time , most of which were based on the day as the base unit, such that the number of units between any two events that happen at the same time of day would be equal to the number of days between them multiplied by some integer power of ten.

In France, a decimal time system in place from to divided the day into 10 hours, each divided into minutes, in turn each divided into seconds; the French Republican Calendar further extended this by assembling days into ten-day "weeks". Ordinal dates and Julian days , the latter of which has seen use in astronomy as it is not subject to leap year complications, allow for the expression of a decimal portion of the day.

In addition to decimal time, there also exist binary clocks and hexadecimal time. The United States-based NASA , when conducting missions to the planet Mars , has typically used a time of day system calibrated to the mean solar day on that planet known as a "sol" , training those involved on those missions to acclimate to that length of day, which is 88, SI seconds, or 2, seconds about 39 minutes longer than the mean solar day on Earth.

NASA's Martian timekeeping system instead of breaking down the sol into 25×53×67 or 25×67×53 SI second divisions slows down clocks so that the hour day is stretched to the length of that on Mars; Martian hours, minutes and seconds are thus 2. The Darian calendar is an arrangement of sols into a Martian year. It maintains a seven-sol week retaining Sunday through Saturday naming customs , with four weeks to a month and 24 months to a Martian year, which contains or sols depending on leap years.

The last Saturday of every six months is skipped over in the Darian calendar. There are two diametrically opposed definitions of the dog year , primarily used to approximate the equivalent age of dogs and other animals with similar life spans. Both are based upon a popular myth regarding the aging of dogs that states that a dog ages seven years in the time it takes a human to age one year.

In fact, the aging of a dog varies by breed larger breeds tend to have shorter lifespans than small and medium-sized breeds ; dogs also develop faster and have longer adulthoods relative to their total life span than humans. Most dogs are sexually mature by 1 year old, which corresponds to perhaps 13 years old in humans. Giant dog breeds and bulldogs tend to have the strongest linear correspondence to human aging, with longer adolescences and shorter overall lifespans; such breeds typically age about nine times as fast as humans throughout their lives.

The galactic year, GY, is the time it takes the solar system to revolve once around the galactic core, approximately million years megaannum or "Ma". It is a convenient unit for long-term measurements. For example, oceans appeared on Earth after 4 GY, life is detectable at 5 GY, and multicellular organisms first appeared at 15 GY. The age of the Earth is estimated at about 20 GY.

KerMetric time is a concept that divides the day into equal parts called Kermits. Each Kermit is equivalent to More precise time can be counted by dividing by or even The name Kermit came from a combination of the surname of the president of the National Research Council in Dr. Larkin Kerwin. The original working model of KerMetric time as conceived by W. Thayer of NRC was assembled by the designated Clock Construction Team of John Phillips, Ron Hawkins, Les Moore and Willie Thayer in A moment was a medieval unit of time.

The movement of a shadow on a sundial covered 40 moments in a solar hour. An hour in this case meant one twelfth of the period between sunrise and sunset. The length of a solar hour depended on the length of the day, which in turn varied with the season , so the length of a moment in modern seconds was not fixed, but on average , a moment corresponded to 90 seconds.

While usually sub-second units are represented with SI prefixes on the second e. These units are occasionally used in astronomy to denote angles. It is named for Alan T. Furman, the American mathematician who adapted the CORDIC algorithm for bit fixed-point arithmetic sometime around There is no consensus as to its name, but it has been called the 8-Bit Furman, the Small Furman, the Furboy and more recently, the miFurman, milli-binary-Furman.

These units are convenient because they form cycles: for the 8-bit unit, the value overflows from to 0 when a full circle has been traversed, so binary addition and subtraction work as expected. Measures are often made using a Gray code , which is trivially converted into more conventional notation. Coordinates were measured in grades on official French terrestrial ordnance charts from the French revolution well into the 20th century. One advantage of this measure is that the distance between latitude lines 0.

Mils and strecks are small units of angle used by various military organizations for range estimation and translating map coordinates used for directing artillery fire. It was introduced by MIT's Instrumentation Laboratories now Draper Labs to measure the performance of inertial navigation systems. In , the United States Environmental Protection Agency introduced the gallon gasoline equivalent as a unit of energy because their research showed most U.

citizens do not understand the standard units. The gallon gasoline equivalent is defined as The energy of various amounts of the explosive TNT kiloton, megaton, gigaton is often used as a unit of explosion energy, and sometimes of asteroid impacts and violent explosive volcanic eruptions.

One ton of TNT produces 4. This definition is only loosely based on the actual physical properties of TNT. The energy released by the Hiroshima bomb explosion about 15 kt TNT equivalent, or 6 × 10 13 J is often used by geologists as a unit when describing the energy of earthquakes , volcanic eruptions , and asteroid impacts.

Prior to the detonation of the Hiroshima bomb, the size of the Halifax Explosion about 3 kt TNT equivalent, or 1. Each explosion had been the largest known artificial detonation to date. A quad is a unit of energy equal to 10 15 BTUs , or approximately 1.

It is suitably large to quantify energy usage by nations or by the planet as whole using everyday numbers. To measure the staggeringly immense amount of energy produced by a supernova , specialists occasionally use the "foe", an acronym derived from the phrase [ten to the power of] f ifty- o ne e rgs, or 10 51 ergs. This unit of measure is convenient because a supernova typically releases about one foe of observable energy in a very short period of time which can be measured in seconds.

The rate at which heat is removed by melting one short ton kg of ice in 24 hours is called a ton of refrigeration, or even a ton of cooling. This unit of refrigeration capacity came from the days when large blocks of ice were used for cooling, and is still used to describe the heat-removal capabilities of refrigerators and chillers today. With the phaseout of the incandescent lamp in the United States and European Union in the early 21st century, manufacturers and sellers of more energy-efficient lamps have compared the visible light output of their lamps to commonly used incandescent lamp sizes with the watt equivalent or watt incandescent replacement usually with a lowercase w as a unit symbol, as opposed to capital W for the actual wattage.

Thus, a watt halogen lamp , a watt compact fluorescent lamp and a watt light-emitting diode lamp , all of which emit lumens of visible light, are all marketed as " watt incandescent replacement" w. The volume of discharge of the Amazon River sometimes used to describe large volumes of water flow such as ocean currents. It is used almost exclusively in oceanography to measure the volumetric rate of transport of ocean currents.

The langley symbol Ly is used to measure solar radiation or insolation. It is equal to one thermochemical calorie per square centimetre 4. Its symbol should not be confused with that for the light-year, ly. Sometimes used to measure the angular drift rate of an inertial navigation system.

It is named after the pioneering radio astronomer Karl Jansky. The brightest natural radio sources have flux densities of the order of one to one hundred jansky. A material-dependent unit used in nuclear and particle physics and engineering to measure the thickness of shielding, for example around a nuclear reactor , particle accelerator , or radiation or particle detector. This unit is commonly used in underground science to express the extent to which the overburden usually rock shields an underground space or laboratory from cosmic rays.

The actual thickness of overburden through which cosmic rays must traverse to reach the underground space varies as a function of direction due to the shape of the overburden, which may be a mountain, or a flat plain, or something more complex like a cliff side. To express the depth of an underground space in mwe or kmwe for deep sites as a single number, the convention is to use the depth beneath a flat overburden at sea level that gives the same overall cosmic ray muon flux in the underground location.

The strontium unit , formerly known as the Sunshine Unit symbol S. It is equal to one picocurie of Sr per gram of body calcium. The permissible body burden was established at 1, S. Bananas, like most organic material, naturally contain a certain amount of radioactive isotopes—even in the absence of any artificial pollution or contamination.

The banana equivalent dose , defined as the additional dose a person will absorb from eating one banana, expresses the severity of exposure to radiation, such as resulting from nuclear weapons or medical procedures, in terms that would make sense to most people. This is approximately 78 nano sieverts — in informal publications one often sees this estimate rounded up to 0.

Utilizing this phenomenon, dose resulting from radiological exposures can be expressed in units of flight-time. Flight-time equivalent dose is defined as the time spent in an aircraft at cruising altitude required to receive a radiological dose approximately equivalent to a radiological exposure such as a medical x-ray. One hour of flight-time is approximately equivalent to a dose of 0.

In measuring unsaturation in fatty acids, the traditional method is the iodine number. Iodine adds stoichiometrically to double bonds, so their amount is reported in grams of iodine spent per grams of oil.

The standard unit is a dimensionless stoichiometry ratio of moles double bonds to moles fatty acid. A similar quantity, bromine number , is used in gasoline analysis. In pulp and paper industry, a similar kappa number is used to measure how much bleaching a pulp requires. Potassium permanganate is added to react with the unsaturated compounds lignin and uronic acids in the pulp and back-titrated. Originally with chlorine bleaching the required quantity of chlorine could be then calculated, although modern methods use multiple stages.

Since the oxidizable compounds are not exclusively lignin and the partially pulped lignin does not have a single stoichiometry, the relation between the kappa number and the precise amount of lignin is inexact.

Gas Mark is a temperature scale, predominantly found on British ovens , that scales linearly with temperature above °C Gas Mark 1 and scales with the log of Celsius below °C.

Demography and quantitative epidemiology are statistical fields that deal with counts or proportions of people, or rates of change in these. Counts and proportions are technically dimensionless , and so have no units of measurement , although identifiers such as "people", "births", "infections" and the like are used for clarity.

Rates of change are counts per unit of time and strictly have inverse time dimensions per unit of time. In demography and epidemiology expressions such as "deaths per year" are used to clarify what is being measured. Prevalence , a common measure in epidemiology is strictly a type of denominator data , a dimensionless ratio or proportion. Prevalence may be expressed as a fraction, a percentage or as the number of cases per 1,, 10,, or , in the population of interest.

A micromort is a unit of risk measuring a one-in-a-million probability of death from micro- and mortality. Micromorts can be used to measure riskiness of various day-to-day activities. A microprobability is a one-in-a million chance of some event; thus a micromort is the microprobability of death.

For example, smoking 1. The large numbers of people involved in demography are often difficult to comprehend. A useful visualisation tool is the audience capacity of large sports stadiums often about , Often the capacity of the largest stadium in a region serves as a unit for a large number of people.

For example, Uruguay's Estadio Centenario is often used in Uruguay , [84] [85] while in parts of the United States, Michigan Stadium is used in this manner. Hence the Melbourne Cricket Ground serves as both a measure of people and a unit of volume. The growth of computing has necessitated the creation of many new units, several of which are based on unusual foundations. Volume or capacity of data is often compared to works of literature or large collections of writing.

Popular units include the Bible, the Encyclopaedia Britannica, phone books, the complete works of Shakespeare , and the Library of Congress. When the Compact Disc began to be used as a data storage device as the CD-ROM , journalists often described the disc capacity megabytes by using the number of Christian Bibles that can be stored.

The King James Version of the Bible in uncompressed plain 8-bit text contains about 4. The print version of the Encyclopædia Britannica is another common data volume metric. It contains approximately million characters, [90] so two copies would fit onto a CD-ROM and still have 50 megabytes or about 11 bibles left over. The term Library of Congress is often used.

It refers to the US Library of Congress. Information researchers have estimated that the entire print collections of the Library of Congress represent roughly 10 terabytes of uncompressed textual data. A measure of quantity of data or information, the " nibble " sometimes spelled "nybble" or "nybl" is normally equal to 4 bits, or one half of the common 8-bit byte. The nibble is used to describe the amount of memory used to store a digit of a number stored in binary-coded decimal format, or to represent a single hexadecimal digit.

Less commonly, 'nibble' may be used for any contiguous portion of a byte of specified length, e. In computing , FLOPS FL oating point O perations P er S econd is a measure of a computer's computing power.

It is also common to see measurements of kilo, mega, giga, and teraFLOPS. It is also used to compare the performance of computers in practice. A measure to determine the CPU speed. It was invented by Linus Torvalds and is nowadays present on every Linux operating system. However, it is not a meaningful measure to assess the actual CPU performance. A computer programming expression, the K-LOC or KLOC, pronounced kay-lok , standing for "kilo- lines of code ", i.

The unit was used, especially by IBM managers, [93] to express the amount of work required to develop a piece of software.

Given that estimates of 20 lines of functional code per day per programmer were often used, it is apparent that 1 K-LOC could take one programmer as long as 50 working days, or 10 working weeks.

This measure is no longer in widespread use because different computer languages require different numbers of lines to achieve the same result occasionally the measure "assembly equivalent lines of code" is used, with appropriate conversion factors from the language actually used to assembly language. Error rates in programming are also measured in "Errors per K-LOC", which is called the defect density. An alternative measurement was defined by Pegasus Mail author David Harris : the "WaP" is equivalent to 71, lines of program code, because that number of lines is the length of one edition of Leo Tolstoy 's War and Peace.

The "tick" is the amount of time between timer interrupts generated by the timer circuit of a CPU. The amount of time is processor-dependent. Chess software frequently uses centipawns internally or externally as a unit measuring how strong each player's situation position is, and hence also by how much one player is beating the other, and how strong a possible move is.

Loss of a pawn will therefore typically lose that player centipawns. The centipawn is often used for comparing possible moves, as in a given position, chess software will often rate the better of two moves within a few centipawns of each other.

The garn is NASA's unit of measure for symptoms resulting from space adaptation syndrome , the response of the human body to weightlessness in space, named after US Senator Jake Garn , who became exceptionally spacesick during an orbital flight in If an astronaut is completely incapacitated by space adaptation syndrome, he or she is under the effect of one garn of symptoms.

Formerly used in real estate transactions in the American Southwest, it was the number of pregnant cows an acre of a given plot of land could support. It acted as a proxy for the agricultural quality, natural resource availability, and arability of a parcel of land.

Numbers very close to, but below one are often expressed in " nines " N — not to be confused with the unit newton , that is in the number of nines following the decimal separator in writing the number in question.

For example, "three nines" or "3N" indicates 0. The dol from the Latin word for pain, dolor is a unit of measurement for pain.

James D. Hardy , Herbert G. Wolff , and Helen Goodell of Cornell University proposed the unit based on their studies of pain during the s and s. They defined one dol to equal to "just noticeable differences" jnd 's in pain. The unit never came into widespread use and other methods are now used to assess the level of pain experienced by patients.

An unusual unit of measurement is a unit of measurement that does not form part of a coherent system of measurement , especially because its exact quantity may not be well known or because it may be an inconvenient multiple or fraction of a base unit.

This definition is not exact since it includes units such as the week or the light-year , which are quite "usual" in the sense that they are often used, but can be "unusual" if taken out of their common context, as demonstrated by the furlong-firkin-fortnight FFF system of units. Many of the unusual units of measurements listed here are colloquial measurements, units devised to compare a measurement to common and familiar objects.

Valve's Source game engine uses the Hammer unit as its base unit of length. This unit refers to Source's official map creation software, Hammer.

This means that 1 Hammer unit is equal to exactly 0. One rack unit U is 1. Rack units are typically denoted without a space between the number of units and the 'U'. Thus a 4U server enclosure case is seven inches The hand is a non- SI unit of length equal to exactly 4 inches It is normally used to measure the height of horses in some English-speaking countries, including Australia, [2] Canada, Ireland, the United Kingdom, and the United States.

The light-nanosecond is defined as exactly It was popularized in information technology as a unit of distance by Grace Hopper as the distance which a photon could travel in one billionth of a second roughly 30 cm or one foot : "The speed of light is one foot per nanosecond. A metric foot , defined as millimetres approximately A Chinese foot is defined as around one third of a meter, depending on jurisdiction.

Horses are used to measure distances in horse racing — a horse length shortened to merely a length when the context makes it obvious equals roughly 8 feet or 2. Shorter distances are measured in fractions of a horse length ; also common are measurements of a full or fraction of a head , a neck , or a nose. In rowing races such as the Oxford and Cambridge Boat Race , the margin of victory and of defeat is expressed in fractions and multiples of boat lengths.

The length of a rowing eight is about 62 feet 19 m. A shorter distance is the canvas , which is the length of the covered part of the boat between the bow and the bow oarsman. The Racing Rules of Sailing also makes heavy use of boat lengths.

A football field is often used as a comparative measurement of length when talking about distances that may be hard to comprehend when stated in terms of standard units.

An American football field is usually understood to be yards 91 m long, though it is technically yards m when including the two 10 yd 9. The field is ft 53 yd; 49 m wide.

An association football pitch may vary within limits of 90— m 98— yd in length and 45—90 m 49—98 yd in width. The usual size of a football pitch is m × 68 m yd × 74 yd , the dimensions used for matches in the UEFA Champions League. A Canadian football field is 65 yd 59 m wide and yd m long, including two 20 yd 18 m long end zones. Sometimes people living in places like Manhattan with a regularly spaced street grid will speak of long blocks and short blocks.

Within a typical large North American city, it is often only possible to travel along east—west and north—south streets, so travel distance between two points is often given in the number of blocks east—west plus the number north—south known to mathematicians as the Manhattan Metric. The radius of Earth, generally given as 6, kilometers 3, miles is often employed as a unit of measure to intuitively compare objects of planetary size.

Lunar distance LD , the distance from the center of Earth to the center of the Moon, is a unit of measure in astronomy. The lunar distance is approximately , km , mi , or 1. A little less than lunar distances make up an astronomical unit. The siriometer is an obsolete astronomical measure equal to one million astronomical units , i.

The name probably derives from early neutron-deflection experiments, when the uranium nucleus was described, and the phrases "big as a barn" and "hit a barn door" were used. Barn are typically used for cross sections in nuclear and particle physics. Additional units include the microbarn or "outhouse" [11] and the yoctobarn or "shed".

One brass is exactly square feet 9. It is also equal, however, to cubic feet 2. This unit is prevalent in the construction industry in India. The square is an Imperial unit of area that is used in the construction industry in North America, [16] and was historically used in Australia by real estate agents.

One square is equal to square feet 9. A roof 's area may be calculated in square feet, then converted to squares. In Ireland, before the 19th century, a "cow's grass" was a measurement used by farmers to indicate the size of their fields.

A cow's grass was equal to the amount of land that could produce enough grass to support a cow. A football pitch , or field, can be used as a man-in-the-street unit of area. An American football field , including both end zones, is by ft A Canadian football field is 65 yards 59 m wide and yards m long with end zones adding a combined 40 yards 37 m to the length, making it 87, square feet 8, m 2 or 0.

An Australian rules football field may be approximately metres yd or more long goal to goal and metres yd or more wide, although the field's elliptical nature reduces its area to a certain extent. A bymetre by yd football field has an area of approximately 15, m 2 1.

A morgen "morning" in Dutch and German was approximately the amount of land tillable by one man behind an ox in the morning hours of a day. The area of a familiar country, state or city is often used as a unit of measure, especially in journalism. Equal to 20, km 2 8, sq mi , the country of Wales is used in phrases such as "an area the size of Wales" [25] or "twice the area of Wales". Ireland is four times as large as Wales, and France is about twenty-five times larger.

The British comedy show The Eleven O'Clock Show parodied the use of this measurement, by introducing a news article about an earthquake in Wales, stating that an area the size of Wales was affected. The Radio 4 programme More or Less introduced the idea of "kilowales" — an area 1, times the size of Wales. The Register introduced the nanowales The measurement has been adopted by rainforest conservation charity Size of Wales , aiming to conserve an area of rainforest equating to the area of Wales.

On 1 March , the charity announced that they had succeeded [29] in conserving an area of rainforest the size of Wales and will continue to operate to sustain and increase the protected area. In the United States, the area of the smallest state, Rhode Island 1, sq mi or 4, km 2 ; the largest of the contiguous 48 states, Texas , sq mi or , km 2 ; and less commonly Alaska , sq mi or 1,, km 2 , the largest of all 50 states, are used in a similar fashion.

For example, Antarctica 's Larsen B ice shelf was approximately the size of Rhode Island until it broke up in Other areas may be described like this, too, like in the movie The China Syndrome when radiation is expected to contaminate "an area the size of Pennsylvania ". The US Central Intelligence Agency uses Washington, D. In the Netherlands, its smallest province, Utrecht 1, km 2 or sq mi , is often used as a comparison for regions in general.

The country of Belgium 30, km 2 or 11, sq mi has also often been used when comparing areas, to the point where it has been regarded as a meme [31] and where there is a website dedicated to notable areas which have been compared to that of Belgium. The Isle of Wight km 2 or sq mi , an island off the south coast of mainland England , is commonly used to define smaller areas.

It has sometimes been used in attempts to examine whether a certain amount of a given object or group would fit in a space its size; in , it was estimated that approximately 2. In Denmark , the island of Bornholm km 2 or sq mi is often used to describe the size of an area. In Germany, the Saarland 2, In Brazil , it is common to compare relatively small areas to the state of Sergipe 21, Smaller areas are sometimes compared to the cities of São Paulo 1, A metric ounce is an approximation of the imperial ounce, US dry ounce, or US fluid ounce.

These three customary units vary. However, the metric ounce is usually taken as 25 or 30 ml when volume is being measured, or grams when mass is being measured. The US Food and Drug Administration FDA defines the "food labeling ounce" as 30 ml, slightly larger than the Several Dutch units of measurement have been replaced with informal metric equivalents, including the ons or ounce. The shot is a liquid volume measure that varies from country to country and state to state depending on legislation.

It is routinely used for measuring strong liquor or spirits when the amount served and consumed is smaller than the more common measures of alcoholic "drink" and "pint". There is a legally defined maximum size of a serving in some jurisdictions. The size of a "single" shot is 20—60 ml 0. The smaller "pony" shot is 20—30 ml 0. According to Encyclopædia Britannica Almanac , a pony is 0.

fluid ounce. In the UK, spirits are sold in shots of either 25 ml approximating the old fluid ounce or 35 ml. A board foot is a United States and Canadian unit of approximate volume, used for lumber.

It is equivalent to 1 inch × 1 foot × 1 foot cu in or 2, cm 3. It is also found in the unit of density pounds per board foot. In Australia and New Zealand the terms super foot or superficial foot were formerly used for this unit.

The exact volume of wood specified is variable and depends on the type of lumber. For planed lumber the dimensions used to calculate board feet are nominal dimensions , which are larger than the actual size of the planed boards.

See Dimensional lumber for more information on this. A system of measure for timber in the round standing or felled , now largely superseded by the metric system except in measuring hardwoods in certain countries. Its purpose is to estimate the value of sawn timber in a log, by measuring the unsawn log and allowing for wastage in the mill.

This translates to a hoppus foot being equal to 1. The hoppus board foot, when milled, yields about one board foot. The volume yielded by the quarter-girth formula is A cubic ton is an antiquated measure of volume, varying based on the commodity from about 16 to 45 cu ft 0. It is now only used for lumber, for which one cubic ton is equivalent to 40 cu ft 1.

The cord is a unit of measure of dry volume used in Canada and the United States to measure firewood and pulpwood.

DEE-ANN DURBIN AP Business Writer. An alternative measurement was defined by Pegasus Mail author David Harris : the "WaP" is equivalent to 71, lines of program code, because that number of lines is the length of one edition of Leo Tolstoy 's War and Peace. In contrast, there is no common usage in which represents anything other than April 3. A metric ounce is an approximation of the imperial ounce, US dry ounce, or US fluid ounce. It was popularized in information technology as a unit of distance by Grace Hopper as the distance which a photon could travel in one billionth of a second roughly 30 cm or one foot : "The speed of light is one foot per nanosecond. This measure is no longer in widespread use because different computer languages require different numbers of lines to achieve the same result occasionally the measure "assembly equivalent lines of code" is used, with appropriate conversion factors from the language actually used to assembly language. Current value is as of , Sunday, December 18, UTC and may be cached.

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