List of strange units of measurement

Strange and whimsical units are sometimes used by scientists, especially physicists and mathematicians, and other technically-minded people such as engineers and programmers, as bits of dry humor combined with putative practical convenience.

Real units — unconventionally scaled

Since SI units have a wide range of scaling prefixes (eg mega-, kilo-, milli-, micro-) it is common humor amongst scientists to pair a really large unit with a small scale prefix — or a very small unit with a large scale prefix:

Attoparsec

Parsecs are used in astronomy to measure enormous interstellar distances; a parsec is approximately 3.26 light-years or 3.085 m. Combining it with the "atto" prefix yields attoparsec, a conveniently human-scaled unit of 3.085 centimeters (about 1 7/32 inches) that has no obvious practical use but does have a proper SI symbol, apc.

Interestingly, 1 attoparsec/microfortnight is nearly 1 inch/second (the actual figure is 1.0043 inch per second or approximately 2.55 cm/s); see mathematical coincidence for a list of similar factoids.

Barn-megaparsec

This unit is similar in concept to the attoparsec, combining very large and small scales. A barn (b) is a unit of cross-sectional area used in nuclear physics, equal to 10^-28m². The "physical cross-section area" of the nucleus of an atom is approximately 1 barn —a very small unit of area (itself humorously named after the proverbial "broad side of a barn"). When this is multiplied by the megaparsec (Mpc) —a very large unit of length— the result is a human-scaled unit of volume approximately equal to 2/3 of a teaspoon.

Light-nanosecond

Beyond its more traditional use as a unit of time, the nanosecond (or light-nanosecond) was popularized 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." In her speaking engagements, she was well-known for passing out light-nanoseconds of wire to the audience, and contrasting it with light-microseconds (a coil of wire 1000 times as long) and light-picoseconds (ground black pepper). Over the course of her life, she had many motivations for this visual aid: including demonstrating the waste of sub-optimal programming, illustrating advances in computer speed, and simply giving young scientists and policy makers the ability to conceptualize the magnitude of very large and small numbers.

Nanoacre

A nanoacre is a unit (about 4 mm²) of real estate on a VLSI chip. "The term gets its humor from the fact that VLSI nanoacres have costs in the same range as real acres in Silicon Valley once one figures in design and fabrication-setup costs."

Nanocentury

Another derived time unit, reducing a rather large time span (century) by preceding it with a fractional prefix (nano). As Tom Duff at Bell Labs pointed out: "How many seconds are there in a year? If I tell you there are 3.155, you won't even try to remember it. On the other hand, who could forget that, to within half a percent, π seconds is a nanocentury."

One computer science professor used to characterize the standard length of his lectures (a little less than an hour) as a microcentury. (roughly 52.6 minutes, accounting for leap years)

SI-Imperial hybrids

In the U.S., new mongrel units are sometimes formed by a combination of traditional units, still widely used, and metric units. Thus, grams per ounce is a common measure used in sports nutrition, for example to measure the density of carbohydrate in a beverage.

A hybrid standard quantity used in mining is the assay ton (AT), which is as many milligrams as there are Troy ounces in an avoirdupois long ton. So to find how many ounces of gold are in a ton of rock, one measures the number of milligrams of gold in an assay ton of rock.

There are also reports of engineers realizing the comfort of base ten SI prefixes, combining them with Imperial or U.S. customary units instead of making the full switch, for example the kiloyard (914.4 m). The kip or kilopound is regularly used in structural engineering. Similarly, the kilofoot is quite common in U.S. telecommunication engineering, as significant distances in cable route planning are usually given in thousands of feet. Instruments like optical time domain reflectometers usually have an option to display results in kft.

Obsolete units used in a modern context.

Another common source of humorous units is to use very obsolete or obscure units in a modern context:

FFF units

Most countries use Le Système International d’Unités (SI). In contrast, the Furlong/Firkin/Fortnight (FFF) system of units of measurement draws its attention by being conservative and off-beat at the same time.

Unit	of	Conventional Imperial unit	SI equivalence
furlong	length	1/8th of a mile	201.168 m
firkin of water	volume	9 Imperial gallons (40.91481 l)	40.91366 kg
fortnight	time	14 days	1,209,600 s

One furlong per fortnight is very nearly 1 centimetre per minute (to within 1 part in 400). Indeed, if the inch were defined as 2.54 cm rather than 2.54 cm exactly, it would be 1 cm/min. Besides having the meaning of "any obscure unit", furlongs per fortnight have also served frequently in the classroom as an example on how to reduce a unit's fraction.

It is perhaps remotely notable that using the FFF system the speed of light may be expressed as being roughly 1.8 terafurlongs per fortnight.

Microfortnight

One very convenient unit deduced from the FFF system is the millionth part of the fundamental timeunit of FFF, which equals 1.2096 seconds, and is a typical example of computer nerd humour. As the story goes, "The VMS operating system has a lot of tuning parameters that you can set with the SYSGEN utility, and one of these is TIMEPROMPTWAIT, the time the system will wait for an operator to set the correct date and time at boot if it realizes that the current value is bogus. This time is specified in microfortnights."

The joke is in having a rather large, obsolete unit (fortnight) combined with a fractional SI prefix (micro) to counteract that. The practical purpose is to discourage setting such parameters without some thought. The unit was selected because the time is only approximately one second, being established by some near-infinite loops rather than a real clock unit (which isn't active at the time), and rather than field complaints about this being "not exactly a second", the unit was invented.

Units for unconventional measurements

Formal scientific measurements of abstract quantities such as 'Beauty', 'Happiness' and 'Comfort' are sadly lacking and many humorists have stepped in to fill the void:

Software failure probability: The Graham and the Barr

The Perl community invented units named after Graham Barr (a Perl release manager) as follows:

A milligraham measures "likely to break in future releases", with IO::* (a collection of Perl packages) calibrated at 1000 milligrahams.
A millibarr measures "violation of good OO principles", with Net::* (a different collection of Perl packages) calibrated at 1000 millibarrs.

The reference is tongue-in-cheek, and has persisted because the unit names are homophones of actual SI units.

Happiness: The Happy

The unit of happiness, coined by Dave Gorman in his television series Important Astrology Experiment. One happy is equal to how much happier you feel if someone gives you a pound coin, which is supposed to be equivalent to how much less happy they feel upon relinquishing it. However this definition seems to fall foul of the law of diminishing returns, which states that the more you have, the less you benefit from having even more. In other words a penniless beggar will gain appreciably from being given a pound, whereas to a millionaire, the donation is trivial.

Beauty: The Helen

The amount of beauty that can launch one thousand ships. Usually used as the millihelen, the amount of beauty that can launch one ship.

Named after the mythological Helen of Troy, from the Iliad. Inspired by Marlowe's line from the play The Tragical History of Doctor Faustus, "Was this the face that launched a thousand ships...?".

Negative values have also been observed—these, of course, are measured by the number of ships sunk or the number of clocks stopped.

Microhelens are, as the unit of beauty required to motivate one sailor, is sometimes given as the units for the common rating-out-of-ten scale of beauty.

Smell: The Hobo Power

Hobo Power is a unit coined by Adam Carolla and Dr. Drew on the radio show Loveline as a measure of how bad something smells. As reference points, 0 HP doesn't smell bad at all, 50 HP is the point at which somebody smelling would throw up (If you were to feed a cat nothing but blue cheese for a week, and it defecates on a hot hibachi, the resulting smoke would measure 50 HP.), and 100 HP, while purely theoretical, would cause death by asphyxiation. A running section of the show involved callers relating foul-smelling situations for which the hosts would then determine the equivalent Hobo Power.

Uncertainty: Microbit

The Finnish computer magazine MikroBitti once claimed to be named after the microbit, defined as one millionth of a bit. In the usual sense of a bit as a discrete entity being either 0 or 1, a fractional bit is not conceptually sound. However, in the sense of information entropy, a bit is a measure of uncertainty. Thus, although this term is never used in practice, a microbit indicates a very small amount of uncertainty. For example, the amount of information corresponding to the knowledge of whether a given second in the 1990s is a leap second is about 0.4 microbits.

Systems support: The Mikrotuki

Literally micro-support. This derives from Finnish mikrotukihenkilö ("microcomputers systems support person"). Originally an in-joke of Nokia Research Center in Helsinki, Finland. It is one workday (8 h or 28 800 seconds) of one competent PC systems support person.

Incompetence: The Pikotuki

Equal to 1/1000 of a nanotuki, or 0.0288 seconds of competent systems support. Likewise originally an inside joke at Nokia Research Center; pikotukihenkilö means "grossly incompetent person assigned in systems support". Also equal to one millionth of a mikrotuki, and used to describe work done by a grossly incompetent work force.

Original Content for Publication: Pub-On

Part unit of measure and part entity-in-itself, the pub-on is the quantum of material submitted to a peer-reviewed journal for publication. Manuscripts barely containing enough new information to qualify as 'original research' are said to consist of a single pub-on, while far-reaching works with many new and interesting results and interpretations might contain many. Publishing papers consisting of only a few pub-ons may make an author's catalogue of papers longer, but will tend to swamp editor's desks and confound the system for other authors.

Seating comfort: The Pinkwater

A notional unit of seating comfort; it can be used to describe both the width of a seat, or the width of a seat which a person needs to be comfortable in. Named for writer and book reviewer Daniel Pinkwater, it was coined by 'Click and Clack', the hosts of the Car Talk radio show. Reputedly, a 1.0 pinkwater seat would be pretty comfortable - most car seats are 0.7 pinkwaters. There was also some discussion of using the pinkwater as a measure of acoustic range - defined by the chord produced by a 1.0 pinkwater person sitting on a piano keyboard.

Fame: The Warhol

Unit of fame or hype, derived from Andy Warhol's dictum "everyone will be world-famous for fifteen minutes" —it represents, naturally, fifteen minutes of fame. Some multiples are:

1 kilowarhol — famous for 15,000 minutes, or 10.42 days. A sort of metric "nine day wonder".
1 megawarhol — famous for 15 million minutes, or 28.5 years. The type of person your parents talk about all the time, but of whom you've never heard from anyone else.

First used by Cullen Murphy in 1999.

Also used simply as meaning 15 minutes; as the Warhol worm, that could infect all vulnerable machines on the entire Internet in 15 minutes or less.

Rate of speech: The Millirubbia (mR)

A millirubbia is a unit of speaking rate, usually applied during a technical talk, derived from Carlo Rubbia, Nobel laureate in physics 1984, who always spoke at 1 R. A normal person spewing forth data at break-neck speed may do perhaps 100 mR.

Bleeding: The Muta

Used to describe how much a professional wrestler bleeds during a match, compared to a New Japan Pro Wrestling match between The Great Muta and Hiroshi Hase on December 14, 1992 in which Muta bled in amounts previously unheard of.

Suckiness: The Lovelace

The newgroup alt.sysadmin.recovery defines 1 Lovelace as "...the amount of force (measured in dynes) it takes to draw a round ball weighing e Troy Ounces down a tube it fits exactly (in air) at a speed of pi attoparsecs/microfortnight." Arguably this is overdefined, as 1 Ll would achieve the goal regardless of the units used to measure the force. The unit is a reference to Deep Throat. (Although in the context of computer systems the name is usually associated with Augusta Ada Lovelace, the unit is not named for her.)

Bogosity: The Lenat

The unit of bogosity, derived from the field of Quantum Bogodynamics, the lenat is seldom used, as it is understood that it is too large for normal conversation. Its most common form is the microlenat.

Units of comparison.

Mainly popularised by journalists seeking to portray sizes or capacities to an audience whom they suppose is incapable of understanding conventional units:

Large areas: Belgium/Wales/Rhode Island/Texas/Alaska/Washington D.C.

The area of a familiar country, state or city is often used as a unit of measure, especially in journalism.

Conservationists discussing the destruction of the Amazon Rainforest often use Belgium as an approximate measure of how much forest is being lost annually. The area of the country of Belgium is 30,528 km². In the United Kingdom, Wales, equal to 20,779 km², is used in phrases such as "an area the size of Wales" or "twice the area of Wales".

In the United States, the areas of Rhode Island (1,545 sq mi), Texas (268,601 sq mi, commonly used due to its historic "larger than life" reputation), and rarely Alaska (656,425 sq mi) are used in a similar fashion, Antarctica's Larsen B ice-shelf was approximately the size of Rhode Island until it broke up in 2002. Due to the Rhode Island being a relatively small unit of measurement (and, perhaps, due to its area being 33% water), many comparisons to the size of Rhode Island are somewhat imprecise. The U.S. Central Intelligence Agency uses Washington, D.C. as a comparison for city-sized objects.

In Finland, the region of Uusimaa (6,366 km²) is conveniently sized for area comparisons.

Data storage capacities: Encyclopedias, Bibles and The Library of Congress

When the compact disc began to be used as a data storage device, the CD-ROM, journalists had to compare the disc capacity (650 MB) to something everyone could imagine. Since nearly every Western households have a Christian Bible, and the Bible is a comparatively long book, it was often chosen for this purpose. The King James Version of the Bible in uncompressed plain 8-bit text contains about 5 million characters, so a CD-ROM can store about 130 Bibles.

The Encyclopædia Britannica is another common data size metric - it contains approximately 300 million characters, two copies would fit comfortably onto a CD-ROM.

The term Library of Congress is sometimes used as a unit of measurement when discussing large amounts of data. It refers to the U.S. Library of Congress. One Library of Congress equals approximately 20 tebibytes of uncompressed textual data.

Hence: 1 Library of Congress = 67,000 Britannicas and 1 Britannica = 60 bibles.

In most cases, diagrams and photographs are not included in the total - since these take considerably more space than text, this would be an important consideration for practical storage of large book collections. In practice, diagrams can often be expressed more compactly using vector graphics, and data compression software can pack more text into the available space. It is possible to compress English text to about 11% of its original size. Thus one might claim that the entire Library of Congress could be packed onto a single 2.2 terabyte storage unit - excluding the pictures.

Bandwidth: Station wagon full of mag-tape

An observation made in the early days of Usenet that the highest bandwidth method of moving networknews across the country was "a station wagon full of mag-tape". The phrase is attributed to many people, including Karl Kleinpaste and Andrew Tanenbaum, and has been subject to countless variations of vehicle and media types (eg "a 747 full of DVDs" or "an intern with a box full of floppies").

As a measurement unit, this is used more as a method of comparison between network technologies than as an actual hard measurement of bandwidth. It also depends crucially on the distance of the communication, e.g. "An ethernet has more bandwidth than an intern with a cartload of CDs" is certainly true over large distances - but is unlikely to be the case for short range communication. This measure also overlooks any latency involved in transferring data between the transport medium and on-line storage, which may be considerable for tape.

Distance: Cigarette

In rural areas of Greece the cigarette was sometimes used as a unit of distance: it would describe the distance someone could travel (on foot or by riding a donkey) in the time needed to smoke a cigarette. The "unit" first appeared around 1900, when cigarettes became popular in Greece, and was used until the 1960s, when automobiles began to displace donkeys and mules. Today, only some aged people in extremely remote villages might still use it.

Until recently, marching pauses in Finnish army might be sometimes measured as "cigarette-long break". This tradition has been discontinued because of the health-hazards in smoking.

It is sometimes used colloquially in Spain as a measure of time equivalent to the time needed to smoke a cigarette during a coffee break. It is roughly equivalent to 5-7 minutes.

Money: Coffee

In Italy, a common monetary unit of measure is the cost of an espresso, which is approximately 0.70 € (average cost).

The term is commonly used in the modern vernacular by salespeople trying to sell you something on the basis of low price —e.g., "For less than the cost of a cup of coffee a day, you can have a brand new {insert item here} in your home". (Alternatively, a can of Coca-Cola is used as the comparison.)

In Denmark, charity organizations such as WWF and Unicef sell subscription memberships by advertising that it's "less than the cost of a pizza a month".

In the United States, the price of a cup of coffee is often used by various world relief fund organizations, e.g. "For less than the cost of a cup of coffee per day, you can feed a hungry orphan in (insert country here)" (again, Coke is also used).

In Greece coffee has been used along with water or a soda drink as monetary unit. When consumers started complaining about the rising prices of gasoline petrol station owners would point out that it cost less than water (about 1 € per liter in kiosks). Soda drinks have been used for comparison —e.g., "For less than the cost of a soda drink per day, you can have a (satellite TV, aircondition etc)in your home". Coffee is less popular because at 3-4.00 € per cup it is seen as expensive

Heights: Double-decker bus

In Britain, newspapers and other media will frequently refer to heights in comparison to the length (8.4 metres) or height (4.4 metres) of a London Routemaster double-decker bus.

Length: Football field

In the United States, this refers to the length American football field, which has a playing area 100 yards (91.44 meters) long. This is often used by the American public media for the sizes of large buildings or parks: easily walkable but non-trivial distances.

In many countries, a football field (or soccer field) is used as a man-in-the-street unit of area.

Laser power: Gillette

A unit described by Theodore Maiman as an early measure of laser output power. The measure was simply the number of razor blades through which the laser could burn a hole. This measurement was especially convenient as the first lasers were pulsed ruby lasers, making it otherwise difficult to measure the output power. Also, due to the relative uniformity of razor blades manufactured by The Gillette Company, it had some usefulness as a rough comparison.

Thus, scientists would brag about having a "4 Gillette" laser versus their competitor's puny "2 Gillette" laser. (For the record, Ted Maiman claims that the first laser was a "2 Gillette" laser.)

Short distances: Hairsbreadth

The thickness of a hair —or more often, specifically "The thickness of a human hair"— generally meaning a distance that's almost but not quite too small to see. The specificity of a human hair is curious since there is no evidence that hair from other mammalian species is any less reliable as a unit of measurement. Webster's Dictionary defines a hairsbreadth as exactly 1/48th inch (0.53 mm) which is curious since the thickness of an actual human hair varies from 1/140th inch (0.18 mm) to 1/1400th inch (0.018 mm) depending on the genetics of the donor, the colour of the hair and from what part of the body the hair was taken. Due to this large range of interpretations, statements such as "half the thickness of a human hair" should be viewed with appropriate skepticism.

Quantity of alcohol: Koskenkorva bottle

In Finland, the standard yardstick for large amounts of alcohol is the Koskenkorva bottle, 0.5 litres at 38%, which works out to be 0.19 litres of pure alcohol. Incidentally, the average yearly consumption of alcohol in Finland, which is about 10 litres per capita, is also 52 Koskenkorva bottles or exactly one Koskenkorva bottle per week.

For example, in an official release of the Finnish Customs: The amount of confiscated alcohol corresponds to 51 000 half-litre Koskenkorva bottles --

Distances: Peninkulma

Possibly from peninkuulema, this was defined as the maximum distance over which you can hear a dog bark. It was originally about 5 km, but in 1655, it was standardized to be equivalent to the Swedish mil, or 10688 m.

Distances: Poronkusema

Poronkusema (literally: passing of water of reindeer) is a measurement of distance originating in Northern Finland. It is the distance travelled in a reindeer pulled sleigh, between two instances of reindeer passing water. This distance is 7.5–10 km. Poronkusemaa kuukaudessa (poronkusemas per month) is Finnish equivalent for furlongs per fortnight or Seemeilen pro Woche. Taken for poronkusema the value of 7500 m, and for month 30 d, poronkusemaa kuukaudessa becomes 0.0289252 m/s.

Distances: Potrzebie

In the 1950s, Mad magazine presented its own system of weights and measures in Donald Knuth's first professionally published article "The Potrzebie System of Weights and Measures" (Mad Magazine #33, June 1957). The basic unit of this system was the potrzebie, which equals the thickness of Mad issue 26, or 2.263348517438173216473 mm.

Scalar: Sagan

A whimsical unit of measure equaling at least 4,000,000,000. Based on the quote "billions of stars" used by Carl Sagan and popularized with the derivation "billions and billions of stars" by Johnny Carson.

Speed: Snail's pace

The speed of a snail. 3 mm/s is reasonable for the European garden snail, Helix aspersa, whose speed is dependent on the surface and ranges from 1.05 mm/s on a paper towel to 2.8 mm/s on Formica. As of 2004 the record speed in the World Snail Racing Championships in Congham, U.K., set in 1995, is 13 inches in 2 minutes = 5.5 mm/s; the Costa Rican mountain snail Velifera can travel 18"/minute = 7.62 mm/s.)

Distance: Smoot

The smoot is a unit of length, defined as the height of Oliver R. Smoot who, fittingly, is a former president of the ISO. The unit is used to measure the length of the Harvard Bridge. Canonically, and originally, in 1958 when Smoot was a student at MIT, the bridge was measured using Mr. Smoot himself as a ruler (his height being 67 inches or 170.18 cm), turning him end over end for the 364.4 (plus one ear) -smoot length of the bridge. The Google Earth software includes the smoot as a measurement unit.

Distance: Stone's throw/Spitting distance

A stone's throw is a measure of distance that can be traced back to the first century (see Luke 22:41 in the Bible), that is used to this day as a very approximate measure. No accurate definition exists, although it is sometimes seen equalled to 25 fathoms (46 m). In most cases "bare et stenkast væk" (Danish, meaning: just one stone's throw away) is taken to mean "quite nearby". Spitting distance is another similar, self-explanatory measurement of distance.

A stone's throw is often used by realtors when describing the location of a house. Their concept is usually different, and in actuality can describe much larger distances.

Volume: Sydharb

A unit of volume used in Australia for water. One sydharb is the amount of water in Sydney Harbour: approximately 500 gigalitres.

Volume: Olympic-sized swimming pool

For smaller volumes of liquid, one measure commonly used in the media in many countries is the Olympic-sized swimming pool. An Olympic-sized swimming pool holds a little over 250,000 litres, that is, 1/2,000,000 of a sydharb.

Height: Tall buildings

In the UK, Nelson's Column is a common measure of height equal to 61.5 m. Used principally by British newspapers or reference books, it is useful in measuring the size of buildings or, occasionally, mountains.

In the USA Buildings such as the Empire State Building (449 m), Sears Tower (519 m), Seattle Space Needle (184 m), or Toronto CN Tower (553 m) are used as comparative measurements of height.

Money: Cases

In the United States, a case is the common name used to refer to a 24-pack of beer. A case of cheap beer, such as Natural Light or Keystone Light, generally costs around 10 dollars (8.2 €). Seeing how beer is a staple among college students, it is understandable that the term "case" is used. For example, a college student might say, "My tuition this year cost me 500 cases!"

Height: Storeys (Stories)

All buildings are made up of storeys (UK and Commonwealth) or stories (US), also referred to as floors or levels. In the United States, each storey is generally 8 to 10 feet (2.4 to 3 meters). The number of stories is used to express the height of a building or nonbuilding structure.

Distance: Blocks

A city block (in most US cities) is between 0.2 and 0.4 km. In Manhattan, the measurement "block" usually refers to a north-south block, which is 1/20 mi (0.08 km). Within a typical large US city, it is only possible to travel along east-west or north-south streets - so a distance measured in blocks is the sum of the number of blocks east-west plus the number north-south (known to mathematicians as the Manhattan distance) rather than 'as the crow flies' where the distance would be the square root of the square of the east-west distance plus the square of the north-south distance, according to Pythagoras' theorem. Hence, distances measured in blocks are not precisely distances in the normal sense.

Distance: Farsee

Used primarily in rural areas while giving directions. It is roughly defined to be as far as one can see. For example, a person could travel two farsees by noting the top of a hill on the horizon, walking to that spot, and then noting the top of the next hill in the same direction, which would mark his destination.

Rare or highly specialised units

These are genuine units for real things - but used in very specialised contexts:

Big Mac index

The Big Mac Index compares the purchasing power parity of countries in terms of the cost a Big Mac hamburger.

Board foot

A board foot is an old American unit of volume, used for wood. It is equivalent to 1 inch x 1 foot x 1 foot, or 144 cubic inches. However, in practice, it is defined differently for hardwood and softwood. It is also found in the unit of density pounds per board foot.

Dunam

In Israel and some other Middle Eastern countries, the dunam (דונם) is the standard unit of land area, defined as 1000 m².

Jansky

In radio astronomy, the unit of electromagnetic flux is the jansky (symbol Jy), equivalent to 10⁻²⁶ watts per square metre per hertz. 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.

Jiffy

In computing, the jiffy is the duration of one tick of the system timer interrupt. Typically, this time is 0.01 seconds, though in some earlier systems (such as the Commodore 8-bit machines) the jiffy was defined as 1/60 of a second, roughly equal to the vertical blanking interval on NTSC video hardware (and the frequency of AC electric power in North America).

KLOC

A computer programming expression, pronounced kay-lok, standing for "Kilo-Lines of Code", i.e. "Thousand Lines of Code". The unit is used, especially by IBM managers, to express the amount of work required to develop a piece of software. Given that estimates of 20 lines of functional bug-free code per day per programmer were often used, it is apparent that 1 KLOC could take one programmer as long as 50 working days, or 10 working weeks.

Langley

The langley unit (symbol Ly) is used to measure solar radiation or insolation. It is equal to one thermochemical calorie per square centimetre (4.184 J/m²) and was named after Samuel Pierpont Langley.

Mache Unit

The Mache Unit, symbol ME (from the German "Mache-Einheit"), is a unit of activity used to gauge mineral springs. It is defined as the quantity of radon per litre which delivers one millionth of a röntgen (that is to say, ionises a sustained current of one StatAmpere, or 10⁻³ esu). This works out to about 1.3468 Bq/m³ (or 0.364 nCi/L)

Metric inch

The U.S. inch is defined to be exactly 25.4 mm. However, this is approximated to 25 mm, to give a "metric inch".

A metric inch was used in some Soviet computers when building from American (pirated) blueprints. The resulting products would seem like their American models but components were not interchangeable.

Nines

Uptime, a measure of the time a computer system has been up and running is sometimes measured in "nines"—that is, the number of "9" digits in the percentage of time the computer is running. For example, "five nines" means 99.999% reliability, which translates to a total downtime of no longer than five minutes per year.

This is also common in describing the purity of copper and other metals; instead of reliability it is purity.

Obscure metric units

There are also some obscure metric units: with arbitrary units and prefixes, you can express a common unit with an unfamiliar term.

For instance, the French at first preferred the are, which is 100 m² (or a tenth of a strema), as base unit for areas; the square metre (m²) becomes a centiare (ca). Only the base unit and hectare (ha) saw a wider use and are still in use in some countries.
Some also used the stere (st) equalling a cubic metre (m³), so the litre (l), which is a cubic decimetre (dm³), becomes a millistere (mst). Motorcyclists are often confused, if the cubic capacity of their engines are given in millilitre (mL) instead of cubic centimetre (cm³); on the contrary the same property for cars is usually given in litres (L), not cubic decimetres (dm³). At the next level, the kilolitre (kL) could replace the cubic metre (m³). The stere is traditionnally used to measure a quantity of wood.
The Finnish term for one cubic metre is motti, "a bound pile of wood", because firewood is usually piled up in cubes one metre on each side. This unit is used only in measuring firewood. (Compare the American use of the rather bigger cord which is about 3.62 m³.) The term has also gained a meaning in military slang. Another unit used in Finland is hehto (hectolitre, 100 liters), for measuring the amount of grains, potatoes or similar.
During the twentieth century, the Soviets and French briefly used a variant of the metric system where the base unit of mass was the tonne. This meant that a kilogram was a millitonne (mt). Conversely, some companies are using the megagram (Mg), to avoid confusion with long or short tons.
In 1793, the French term "grave" (from "gravity") was suggested as the base unit of mass for the metric system. In 1795, however, due in no small part to the French Revolution, the name "kilogram" was adopted instead. Now, thanks to this historical quirk, we have a base unit that includes a prefix.
A mil in Norway and Sweden is a distance of 10 kilometres. The term originates from a pre-metric mil (in earlier times rast) of slightly over 10 km, denoting a suitable distance between rests when walking. It was complemented by a smaller unit, the skogsmil (English: forest mile), which was roughly 5 km. The metric mil was officially established in Sweden on 1 January 1889. For geographical distances the term is probably used more than the kilometre. It is also used commonly for measuring vehicle fuel consumption, litres per mil means litres consumed per 10 km. Confusingly, however, the mil is also a much smaller unit equal to one-thousandth of an inch and an angular unit of measure.
In some parts of central Europe decagrams are used in cooking and food retail. In Austria the unit is simply referred to as Deka.
Among physicists there is the in-joke replacing common units with uncommon units, as in velocity: metres per second = hertz per dioptre (Hz/dpt). In this case, the reciprocal values of metre and second —dioptre and hertz, respectively— are used to contrive the same unit.
The unit of perceived loudness, phon, is sometimes also called as phone. This has led to puns such as One megaphone equals 10¹² microphones.

Morgan

The morgan is a rarely-used unit related to the distance between genes on a chromosome. Only a daughter unit, the centimorgan, is commonly used. In humans, the morgan would be approximately 100 million base pairs long.

Nibble

A measure of quantity of data or information, the "nibble" (sometimes spelled "nybble") is equal to 4 bits, or one half of the common 8-bit byte. Rarely used, it is seldom seen outside of computer science labs.

Stokes

One of the few CGS units to see wider use, one stokes is a unit of kinematic viscosity, defined as 10^-4 m²/s, ie. 1 cm²/s.

Scoville heat unit

The Scoville scale is a measure of the hotness of a chilli pepper. It's the degree of dilution in sugar water of a specific chilli pepper extract when a panel of 5 tasters can no longer detect its 'heat'. Blair's 16 Million Reserve is supposed to be the top of the scale, allegedly containing pure capsaicin and providing 1.6x10⁷ SHU.

Siriometer

The siriometer is a rarely used astronomical measure equal to one million Astronomical Units, i.e., one million times the average distance between the Sun and Earth. This distance is equal to about 15.8 light years, about twice the distance from Earth to the star Sirius.

Sunshine unit

The Sunshine Unit, also known as the Strontium Unit (symbol S.U.) is a unit of biological contamination by radio-active substances (specifically Strontium-90). It is equal to one picocurie of Sr-90 per gram of body calcium. Since about 2% of the human body mass is calcium, and Sr-90 has a half-life of 28.78 years, releasing 6.697+2.282 MeV per disintegration, this works out to about 1.065 Gy/s. The permissible body burden was established at 1000 S.U.

Vodka index

The Vodka index is the relation between the price of a liter of standard vodka, and the mean price of a hardbound book in a particular country. While somewhat jocular, it is purported to evince how well literacy fares in a given country. Among its many proponents are included Al Alvarez and science fiction author Harry Harrison.

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