List of non-coherent units of measurement facts for kids

Have you ever heard someone say a building is "as tall as 10 football fields"? Or that a computer can do "a million calculations per second"? These are examples of unusual units of measurement! While we often use standard units like meters, kilograms, and seconds, people sometimes create or use other units that are more relatable or specific to a certain job. This article explores some of these interesting and unique ways we measure the world around us. Many of these units are based on everyday objects or specific situations, making them easier to understand in certain contexts.

Measuring Length in Fun Ways

Ligne: For Buttons!

Have you ever wondered how button sizes are measured? They often use a unit called the ligne (pronounced "leen"). This measurement tells you the diameter (width) of a button. There are 40 lignes in 1 inch. So, a button that's 20 lignes wide is half an inch across!

Hammer Unit: In Video Games

In some video games, like those made with Valve's Source engine, distances are measured in Hammer units. This unit is named after the software used to create the game maps. The exact size can change between games, but usually, 16 Hammer units equal 1 foot. This means 1 Hammer unit is about 0.75 inches (3⁄4″) or 19.05 millimetres.

Rack Unit: For Electronics

A typical section of rack rail, showing rack unit distribution

When you see tall cabinets filled with computer servers or sound equipment, their height is often measured in rack units (U). One rack unit is exactly 1.75 inches (44.45 mm) tall. So, a "4U server" is about seven inches (177.8 mm) high. This unit helps make sure all equipment fits perfectly into standard racks.

Hand: For Horses

The hand is a special unit used to measure the height of horses. One hand is exactly 4 inches (101.6 mm). You'll hear this in countries like the UK and USA. When someone says a horse is "15.1 hands," it means 15 hands and 1 inch, not 15.1 hands as a decimal.

Light-Nanosecond: Speed of Light

Grace Hopper distributed lengths of wire approximately 1 light-nanosecond long in lectures, to remind students not to waste nanoseconds

A light-nanosecond is the distance light travels in one billionth of a second. This is about 30 centimeters (or one foot)! Grace Hopper, a famous computer scientist, used to give out pieces of wire this length in her lectures to show how fast computers work and why we shouldn't waste even a nanosecond of time.

Metric Foot: A Different Foot

Sometimes, people have tried to create a "metric foot" that's 300 millimetres (approximately 11.8 inches). This was occasionally used in the UK but never became official. Interestingly, a "metric inch" of 25 millimetres (0.984 in) was used in Soviet microchips, which sometimes caused problems because they were slightly different from US-made parts.

Horse Length: In Racing

In horse racing, distances are often measured in horse lengths. One horse length is roughly 8 feet or 2.4 metres. For very close races, they might even use smaller units like a "head," "neck," or "nose" to describe the winning margin!

Boat Length: For Rowing Races

In rowing races, like the famous Oxford and Cambridge Boat Race, the difference between boats is measured in boat lengths. A racing boat (an "eight") is about 62 feet (19 m) long. Sometimes, this is also described in seconds, like "3 seconds ahead."

Football Field: A Common Comparison

A football field is a very popular way to describe large lengths that are hard to imagine otherwise.

• An American football field is usually 100 yards (91 m) long (or 120 yards (110 m) if you include the end zones).
• An association football pitch (soccer field) can be between 90–120 m (98–131 yd) long. The recommended size for big games is 105 m × 68 m (115 yd × 74 yd).

Block: City Distances

In many cities, especially in the US, people use the term block to describe distances. A city block is usually between 1⁄16 and 1⁄8 mi (100 and 200 m). In places with a grid pattern, like Manhattan, people might talk about "long blocks" and "short blocks" to give directions.

Earth Radius: For Giant Objects

The average radius of Earth (about 6,371 kilometers or 3,959 miles) is often used to compare the size of very large objects, especially in space. It helps us understand just how big planets or other celestial bodies are.

Lunar Distance: To the Moon and Back

Lunar distance (LD) is the distance from the center of Earth to the center of the Moon. It's about 384,400 km (238,900 mi), or 1.28 light-seconds. This unit helps astronomers talk about distances to objects near Earth.

Measuring Area in Unique Ways

Barn: For Tiny Particles

A barn is a super tiny unit of area, equal to 10⁻²⁸ square meters! It's used in nuclear physics to measure the size of atomic particles, like a uranium nucleus. The name comes from scientists joking that these tiny particles were "as big as a barn" when they first studied them.

Kuang: A Chinese Area Unit

A kuang is a traditional Chinese unit of area. It's equal to 0.11 square meters, or one square Chinese foot. It's a glimpse into how different cultures have measured land.

Brass or Square: In Construction

In the construction world, especially in India and North America, a brass or square is used to measure area. One brass is exactly 100 square feet (9.29 m²). It's used for things like plastering or painting. In North America, a "square" is also used for roofing.

Cow's Grass: Old Irish Farms

Before the 1800s in Ireland, farmers used a unit called a cow's grass. This was the amount of land that could grow enough grass to feed one cow. It's a very practical and natural way to measure land!

Football Field: For Large Areas

On this schema, an association football field is used to help to conceptualize the size of a polo field.

Just like for length, a football field is often used to describe large areas.

• A standard FIFA association football pitch is 105 m (344 ft) long by 68 m (223 ft) wide, which is about 7,140 m² or 0.714 ha or 1.76 acres.
• An American football field (including end zones) is about 57,600 square feet (5,350 m²) (0.535 hectares or 1.32 acres).
• An Australian rules football playing field is even bigger, about 15,900 m² (1.59 ha; 3.9 acres), which is roughly three times the size of an American football field!

Morgen: A Morning's Work

A morgen (meaning "morning" in Dutch and German) was originally the amount of land a person could plow with an ox in one morning. This was an official unit in South Africa until the 1970s, where 1 morgen equals 0.856532 hectares.

Countries, Regions, and Cities: Comparing Sizes

Republic of Ireland (grey), Wales (red), and the remainder of the United Kingdom (pink)

Journalists often compare the size of something to a familiar country, state, or city. For example, you might hear that a forest fire covered "twice the area of Wales" (Wales is 20,779 square kilometers or 8,023 square miles). This helps people quickly understand how big something is.

Measuring Volume in Different Ways

Metric Ounce: An Approximation

A metric ounce is an informal way to describe a volume of liquid, usually 25 or 30 ml (0.88 or 1.06 imp fl oz; 0.85 or 1.01 US fl oz). It's an approximation of older "ounce" units, which varied a lot. For example, the US Food and Drug Administration defines a "food labeling ounce" as 30 ml (1.1 imp fl oz; 1.0 US fl oz).

Shot: For Small Liquids

Three shot glasses of varying shapes and sizes

A shot is a small measure of liquid volume. Its size can vary, but a "single" shot is usually between 20–60 ml (0.70–2.11 imp fl oz; 0.68–2.03 US fl oz). In the UK, spirits are sold in shots of either 25 ml (0.88 imp fl oz; 0.85 US fl oz) or 35 ml (1.2 imp fl oz; 1.2 US fl oz).

Board Foot: For Lumber

A board foot is a unit used in the United States and Canada to measure lumber (wood). It's equal to a piece of wood that is 1 inch thick, 1 foot wide, and 1 foot long, which is 144 in³ or 2,360 cm³.

Cord and Rick: For Firewood

A cord of wood

A cord is a unit for measuring firewood. It's the amount of wood that, when stacked neatly, fills a space of 128 cubic feet (3.62 m³). This is usually a pile 4 feet deep, 4 feet high, and 8 feet wide. A "rick" or "face cord" is a smaller, less standardized amount, often 1⁄3 of a cord.

Twenty-Foot Equivalent Unit: For Shipping Containers

The twenty-foot equivalent unit (TEU) is a unit of volume based on the smallest standard shipping container. It's equal to 1,172 cubic feet (33.2 m³). Large container ships have their capacity measured in how many TEUs they can carry.

Acre-Foot: For Water Resources

An acre-foot is a unit of volume used in the United States for large amounts of water, like in reservoirs or rivers. It's the amount of water that would cover one acre of land to a depth of one foot. This is about 43,560 cu ft (1,233 m³; 325,851 US gal; 271,328 imp gal).

Casual Units: Everyday Comparisons

Many well-known objects are used as informal units of volume:

• Double-decker bus: Sometimes used to describe the size of a hole in the ground, like "a 4 DDB hole."
• Olympic-size swimming pool:
  

  An Olympic-size swimming pool holds over 2 acre-feet of water
  This is a very common way to describe large volumes of liquid. An Olympic pool holds about 2,500 m³ (660,000 US gal) of water.
• Royal Albert Hall: A large concert hall in the UK, sometimes used to describe volumes of trash in landfills. Its auditorium holds between 85,000 and 99,000 cubic meters.
• Melbourne Cricket Ground: A huge stadium in Australia, its volume (1,574,000 cubic meters) is used to compare large volumes, like "630 Olympic swimming pools."
• Sydney Harbour:
  

  Sydney Harbour (Port Jackson)
  In Australia, the amount of water in Sydney Harbour (about 562 gigalitres or 562,000,000 cubic meters) is used to describe very large water volumes.
• The Grand Canyon: For truly enormous volumes, the Grand Canyon (about 4,170 km³) is used to visualize things like underground magma chambers.

Measuring Flow Rate

Miner's Inch: For Water Flow

The miner's inch is an old unit that measures the volume of water flowing through a one-square-inch opening in a certain amount of time. Its exact size varied depending on the location.

Measuring Mass in Special Ways

Grave: An Early Metric Idea

In 1793, when the metric system was being developed in France, the term "grave" was suggested as the basic unit of mass. However, in 1795, the name "kilogramme" was chosen instead.

Bag of Cement: In Construction

In the construction industry, a "bag of cement" is often defined as 94 lb (43 kg) because it takes up about 1 cubic foot (28 litres) of space. When ordering concrete, a "5 bag mix" means the concrete will be made with 5 bags of cement per cubic yard.

Jupiter: For Planets

Jupiter

When astronomers talk about the masses of planets outside our Solar System, they often compare them to the mass of Jupiter. For example, they might say a new planet has "3 Jupiters" of mass. Jupiter's mass is about 1.9 × 10²⁷ kilograms.

Sun: For Stars and Galaxies

Solar mass is used in astronomy to measure the masses of stars and galaxies. One Solar mass is about 2.0 × 10³⁰ kilograms. For example, the Milky Way galaxy has a mass of approximately 6 × 10¹¹ Solar masses! This unit is also helpful for calculating how long planets take to orbit stars.

Measuring Time in Different Ways

Light-Distance: Time for Light to Travel

Just as a light-year is a distance, a "light-foot" or "light-mile" can be used to describe time. A light-foot is the time it takes for light to travel one foot, which is about one nanosecond. A light-mile is about five microseconds.

Shake: A Very Short Time

In nuclear science, a shake is a very short period of time, defined as 10 nanoseconds. It's used when talking about extremely fast events.

Jiffy: In Computers

In computing, a jiffy is the time between "ticks" of a computer's internal timer. This is usually 0.01 seconds. In older systems, it was sometimes 1⁄60 of a second.

Thirds, Fourths: Dividing Seconds

We know a minute is 1⁄60 of an hour, and a second is 1⁄60 of a minute. This system can go further! A "third" would be 1⁄60 of a second (about 16.7 milliseconds), and a "fourth" would be 1⁄60 of a third (about 278 microseconds). These are sometimes used in astronomy for very precise angle measurements.

Moment: A Medieval Time Unit

A moment was a unit of time used in the Middle Ages. It was based on the movement of a shadow on a sundial. There were 40 moments in a "solar hour," which changed with the seasons. On average, a moment was about 90 seconds long.

Sidereal Day: Earth's True Spin

A sidereal day is how long it takes Earth to rotate once compared to distant stars, not the Sun. It's about 23 hours, 56 minutes, and 4 seconds, which is slightly shorter than our regular 24-hour day.

Decimal Time Systems: Different Clocks

Decimal time clock reading 2.50 DT, equivalent to 6 AM standard time.

Throughout history, people have tried to divide the day into units based on 10. In ancient China, a kè was 1⁄100 of a day. During the French Revolution, they even tried a system with 10 hours in a day, 100 minutes in an hour, and 100 seconds in a minute!

Sol: A Martian Day

When NASA sends missions to Mars, they use a special unit of time called a sol, which is a Martian day. A sol is about 88,775 seconds, or about 39 minutes longer than an Earth day. Scientists and engineers working on Mars missions often adjust their schedules to "Mars time."

Dog Year: A Common Myth

You've probably heard the saying that "one human year is seven dog years." This idea led to the unit of a dog year. However, it's a myth! Dogs age differently depending on their breed, and they mature much faster than humans.

Galactic Year: Cosmic Time

A galactic year (GY) is the time it takes for our entire Solar System to orbit the center of the Milky Way galaxy. This takes about 250 million years! It's a useful unit for talking about very long periods in cosmic history. For example, oceans appeared on Earth about 4 GY ago.

Measuring Angles in Unique Ways

Mils, Strecks: For Military Use

Estimating mils by hand

Mils and strecks are small units of angle used by different military groups. They help soldiers estimate distances and direct artillery fire. The exact size varies: NATO uses 6400 mils in a full circle, while some other groups use 6000 or 6300.

Grade (also grad, gradian, gon): A Decimal Angle

A grade (also called a gradian or gon) is a unit of angle where a right angle is 100 grades. So, a full circle is 400 grades. One advantage is that the distance between lines of latitude 0.01 grades apart at the equator is almost exactly 1 kilometer.

Measuring Energy in Special Ways

Gasoline Gallon Equivalent: For Fuel

In the United States, the gallon gasoline equivalent (GGE) was introduced to help people understand the energy content of different fuels. It's defined as 33.7 kilowatt-hours, which is about 1.213 × 10⁸ joules. This unit helps compare the efficiency of electric cars to gasoline cars.

Tons of TNT Equivalent: For Explosions

The energy of large explosions, like volcanic eruptions or asteroid impacts, is often measured in tons of TNT equivalent. One ton of TNT produces 4.184 × 10⁹ joules of energy. This unit helps scientists compare the power of very strong events.

Hiroshima Bomb and Halifax Explosion: Historical Energy Comparisons

Hiroshima bomb explosion

Halifax explosion

Before the 1940s, the Halifax Explosion (about 1.26 × 10¹³ joules) was the largest known artificial explosion. Later, the energy of the Hiroshima bomb (about 6 × 10¹³ joules) became a new standard for comparing the energy of earthquakes, volcanic eruptions, and asteroid impacts. These units help scientists put massive energy releases into perspective.

Quad: For National Energy Use

A quad is a very large unit of energy, equal to 10¹⁵ British Thermal Units (BTUs), or about 1.055 × 10¹⁸ joules. It's used to measure the total energy consumption of entire countries or even the whole planet. For example, in 2004, the US used about 100 quads of energy.

Foe: For Supernovae

A foe is an incredibly huge unit of energy, equal to 10⁴⁴ joules. It was created by physicist Gerry Brown to measure the staggering amount of energy released by a supernova (an exploding star). A supernova typically releases about one foe of energy in a very short time.

Other Interesting Units

Ton of Refrigeration: For Cooling Power

A ton of refrigeration (or ton of cooling) measures how much heat a cooling system can remove. It's based on the amount of heat needed to melt one short ton of ice in 24 hours. One ton of refrigeration is equal to 12,000 BTUs per hour, or 3.517 kilowatts.

Watt Equivalent: For Light Bulbs

With the rise of energy-efficient light bulbs, manufacturers use "watt equivalent" to compare their brightness to old incandescent bulbs. For example, a 14-watt LED bulb might be marketed as a "100-watt incandescent replacement" because it produces the same amount of visible light (1500 lumens).

Amazon River: For Huge Water Flows

The massive volume of water discharged by the Amazon River is sometimes used as a unit to describe other large water flows, like ocean currents. This unit is equivalent to 216,000 cubic meters per second!

Sverdrup: For Ocean Currents

One sverdrup (Sv) is equal to 1,000,000 cubic meters per second. It's used almost only in oceanography to measure the huge flow rates of ocean currents.

Bubnoff Unit: For Erosion Speed

The Bubnoff unit measures how fast Earth's surface is lowered by erosion. It's defined as one micrometer per year, or one millimeter every 1,000 years. This helps geologists study how landscapes change over very long periods.

Langley: For Solar Radiation

The langley (Ly) is a unit used to measure solar radiation, or how much sunlight hits a surface. It's equal to one thermochemical calorie per square centimeter.

MERU: For Angular Speed

A MERU (milli Earth rate unit) measures angular velocity, which is how fast something is spinning. It's equal to 1⁄1000 of Earth's rotation rate. It was developed to measure the performance of inertial navigation systems, like those in rockets or submarines.

Jansky: For Radio Waves

In radio astronomy, the jansky (Jy) measures the strength of radio waves coming from space. It's a very small unit, equal to 10⁻²⁶ watts per square meter per hertz. The brightest natural radio sources have flux densities of about one to one hundred jansky.

Gas Mark: For Oven Temperatures

Gas Mark is a temperature scale mainly found on British ovens. It's a simple numbering system for oven settings, where Gas Mark 1 is 135 °C (275 °F), and the numbers increase for hotter temperatures.

People and Information

Micromort: Measuring Risk

A micromort is a unit of risk that measures a one-in-a-million chance of death. It helps us understand the riskiness of everyday activities. For example, traveling 370 km (230 miles) by car increases your death risk by one micromort.

Stadium Capacities: For Crowds

To make large numbers of people comprehensible, the capacity of large stadiums is often used. Here the Melbourne Cricket Ground (MCG) is in the process of filling with 100,016 spectators on AFL grand final day in 2010.

When talking about very large numbers of people, like populations or event attendees, it can be hard to imagine. So, people often compare these numbers to the capacity of large sports stadiums. For example, the Melbourne Cricket Ground in Australia holds about 100,000 people, so you might hear "a crowd the size of the MCG."

Data Volume: Comparing to Books

A CD-ROM can easily store the entirety of a paper encyclopedia's words and images, plus audio and video clips

The amount of digital data is often compared to famous books or collections of writing.

• A CD-ROM (650 megabytes) can store about 150 copies of the King James Version of the Bible.
• The entire print version of the Encyclopædia Britannica (about 300 million characters) would fit on two CD-ROMs.
• The entire print collection of the US Library of Congress is estimated to be about 10 terabytes of text!

Nibble: A Small Piece of Data

A nibble (sometimes spelled "nybble") is a small unit of data, usually 4 bits, which is half of a common 8-bit byte. It's used to store a single digit in some computer formats.

FLOPS: Computer Speed

FLOPS stands for FLoating point Operations Per Second. It measures how many calculations a computer can do in one second. You'll often hear about megaFLOPS (millions of calculations) or gigaFLOPS (billions of calculations).

BogoMips: A "Fake" Speed Test

BogoMips is a measure of CPU speed that was created by Linus Torvalds for the Linux operating system. It's not a truly accurate way to compare computer performance, but it's a fun, quirky unit.

KLOC: For Software Code

KLOC (pronounced "kay-lok") stands for "kilo-lines of code," meaning a thousand lines of computer code. This unit was used to estimate how much work was needed to develop software. For example, 1 KLOC could take a programmer about 50 working days!

Ticks: In Games and Computers

A tick is the amount of time between updates in a computer program or video game. For example, Minecraft servers process the game world at 20 ticks per second. Other games might use 30, 60, or even 128 ticks per second for smoother gameplay.

Other Unique Measurements

Centipawn: In Chess

In chess software, a centipawn is a unit that measures how strong a player's position is. 100 centipawns are roughly equal to the value of one pawn. Chess programs use this to compare different moves and see which one is better.

Garn: For Spacesickness

The garn is a unit created by NASA to measure how severe space adaptation syndrome (spacesickness) is for astronauts. It's named after US Senator Jake Garn, who got very spacesick during a space flight in 1985. If an astronaut is completely unable to function due to spacesickness, they are experiencing "one garn" of symptoms.

Mother Cows: For Land Quality

In the American Southwest, people once used "mother cows" to describe the quality of land. It was the number of pregnant cows an acre of land could support. This showed how fertile and resourceful the land was for farming.

Nines: For Purity and Reliability

1 troy ounce (31 g) of four nines fine gold (999,9)

The term "nines" (N) is used to describe how close a number is to 1. For example, "three nines" or "3N" means 0.999 or 99.9%.

• It's used for the reliability of computer systems. "Five nines" reliability means a system is working 99.999% of the time, which is less than five minutes of downtime per year!
• It also describes the purity of materials, like "four nines fine gold" (99.99% pure).

Dol: A Unit of Pain

The dol (from the Latin word for pain, dolor) was a unit proposed in the 1940s to measure pain. One dol was defined as a "just-noticeable difference" in pain. However, this unit never became widely used, and other methods are now used to assess pain.

Pepper Heat: Scoville Units

Chili peppers.

Have you ever wondered how spicy a chili pepper is? The Scoville scale measures the "hotness" of chili peppers. It's based on how much a chili extract needs to be diluted in sugar water before tasters can no longer feel the heat. Pure capsaicin, the chemical that makes peppers hot, has 16 million Scoville heat units! The ASTA (American Spice Trade Association) also has a pungency unit, where Scoville units are roughly 15 times smaller.

Savart: For Sound Pitch

The savart is an old unit from the 18th century used to measure the frequency ratio of two sounds, or how far apart their pitches are. It's equal to 1⁄1000 of a decade. Today, the "cent" is more commonly used in music.

See also

• GNU Units, a unit conversion program, which supports many uncommon units
• List of humorous units of measurement
• List of obsolete units of measurement