This is a list of units of measurement in active use, which do not form part of a coherent system of measurement. Many of the items listed here are colloquial units based on familiar objects such as parts of the body. Many of the listed units are approximate or vaguely defined. Some are odd multiples or fractions of a base unit.
Length
Ligne The ligne is a French unit of length that is sometimes used in watchmaking and ribbon manufacture. It is equal to one twelfth of a Paris inch, or about 2.2558 mm.
Diameters of buttons are also measured in a unit called the ligne, but it is defined as 1/40 inch.
Vee In groff/troff and specifically in the included traditional manuscript macro set ms, the vee (v) is a unit of vertical distance often—but not always—corresponding to the height of an ordinary line of text.
Horizontal pitch Horizontal pitch (HP) is a unit of length defined by the Eurocard printed circuit board standard used to measure the horizontal width of rack-mounted electronic equipment, similar to the rack unit (U) used to measure vertical heights of rack-mounted equipment. One HP is 0.2 inches (″) or wide.
Rack unit
One rack unit (U) is and is used to measure rack-mountable audiovisual, computing and industrial equipment. Rack units are typically denoted without a space between the number of units and the 'U'. Thus, a 4U server enclosure (case) is nominally high, or more precisely, built to occupy a vertical space seven inches high, with sufficient clearance to allow movement of adjacent hardware.
Hand
The hand is a non-SI unit of length equal to exactly . It is normally used to measure the height of horses in some English-speaking countries, including Australia, Canada, Ireland, the United Kingdom, and the United States. It is customary when measuring in hands to use a point to indicate inches (quarter-hands) and not tenths of a hand. For example, 15.1 hands normally means 15 hands, 1 inch (5 ft 1 in), rather than hands.
Light-nanosecond
The light-nanosecond is defined as exactly 29.9792458 cm. 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."
Metric foot
A metric foot, defined as ), has been used occasionally in the UK but has never been an official unit.
The corresponding metric inch of was used for pin spacing in Soviet microchips, which were often cloned from Western designs but scaled down slightly from US customary inches to metric inches. This led to incompatibility issues in the Soviet computer market.Fred Langa, "An Editor's View" sidebar to "Computing in the U.S.S.R.", April 1991 BYTE Magazine, page 129
Horse
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 . 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.
Boat length In rowing races such as the Oxford and Cambridge Boat Race, the margin of victory or defeat is expressed in fractions and multiples of boat lengths. The length of a rowing eight is about . This is also commonly expressed in time i.e. 3 or 3.5 seconds. A shorter distance is the canvas, which is the length of the covered part of the boat between the bow and the bow oarsman, and equivalent to less than one second. The Racing Rules of Sailing also makes heavy use of boat lengths.
Football field (length) 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 long, though it is technically when including the two long end zones. The field is wide.
An association football pitch may vary within limits of in length and in width. The recommended field size is for major competitions such as the FIFA World Cup, UEFA European Championship and UEFA Champions League.
A Canadian football field is wide and long, including two long end zones.
Block In most US cities, a city block is between . In Manhattan, the measurement "block" usually refers to a north–south block, which is . 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 distance).
Earth radius The globally-average radius of Earth, generally given as 6,371 kilometres (3,959 miles), is often employed as a unit of measure to intuitively compare objects of planetary size.
Lunar distance Lunar distance (LD), the distance from the centre of Earth to the centre of the Moon, is a unit of measure in astronomy. The lunar distance is approximately , or 1.28 light-seconds; this is roughly 30 times Earth's diameter. A little less than 400 lunar distances make up an astronomical unit.
Area
Barn
One barn is 10−28 square metres, about the cross-sectional area of a uranium nucleus. 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") and the yoctobarn (or "shed").
Brass or square One brass is exactly area (used in measurement of work done or to be done, such as plastering, painting, etc.). The same word is used, however, for of estimated or supplied loose material, such as sand, gravel, rubble, etc. This unit is prevalent in the construction industry in India.
The same area is called a square in the construction industry in North America, and was historically used in Australia by real estate agents. A roof's area may be calculated in square feet, then converted to squares.
Football field (area)
A football pitch, or field, can be used as a man-in-the-street unit of area. The standard FIFA football pitch for international matches is long by wide (); FIFA allows for a variance of up to in length in either direction and more or less in width (and larger departures if the pitch is not used for international competition), which generally results in the association football pitch generally only being used for order of magnitude comparisons.
An American football field, including both end zones, is , or (). A Canadian football field is wide and long with end zones adding a combined to the length, making it or .
An Australian rules football field may be approximately (or more) long goal to goal and (or more) wide, although the field's elliptical nature reduces its area to a certain extent. A football field has an area of approximately , twice the area of a Canadian football field and three times that of an American football field.
Countries, regions, and cities
The area of a familiar country, state or city is often used as a size reference, especially in journalism. Usually the region is used to describe something of similar size to the reference region, but in some cases such references become common enough that multiples of the area start to be used, as in "twice the area of Wales". Besides Wales (20,779 km2 or 8,023 mi2), other regions that have been used this way include Belgium (), the German state of Saarland (), and Washington, D.C. ().
Volume
Metric ounce 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 when volume is being measured, or in grams when mass is being measured.
The US Food and Drug Administration (FDA) defines the "food labeling ounce" as , slightly larger than the fluid ounce.For Nutrition facts labeling "a teaspoon means 5 milliliters (ml), a tablespoon means 15 ml, a cup means 240 ml, 1 fl oz means 30 ml, and 1 oz in weight means 28 g".
Several Dutch units of measurement have been replaced with informal metric equivalents, including the ons or ounce. It originally meant of a pound, or a little over depending on which definition of the pound was used, but was redefined as when the country metricated.
Shot
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 . The smaller "pony" shot is . According to Encyclopædia Britannica Almanac 2009, a pony is 0.75 fluid ounces of liquor. According to Wolfram Alpha, one pony is 1 U.S. fluid ounce. "Double" shots (surprisingly not always the size of two single shots, even in the same place) are . In the UK, spirits are sold in shots of either (approximating the old fluid ounce) or .
Board foot or super foot
A board foot is a United States and Canadian unit of approximate volume, used for lumber. It is equivalent to (). 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.
Hoppus foot
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. Following the so-called "quarter-girth formula" (the square of one quarter of the circumference in inches multiplied by of the length in feet), the notional log is four feet in circumference, one inch of which yields the hoppus board foot, 1 foot yields the hoppus foot, and 50 feet yields a hoppus ton. This translates to a hoppus foot being equal to . The hoppus board foot, when milled, yields about one board foot. The volume yielded by the quarter-girth formula is 78.54% of cubic measure (i.e. 1 ft3 = 0.7854 h ft; 1 h ft = 1.273 ft3).
Cubic ton
A cubic ton is an antiquated measure of volume, varying based on the commodity from about . It is now only used for lumber, for which one cubic ton is equivalent to .
Cord and rick
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 . This corresponds to a well-stacked woodpile, 4 feet deep by 4 feet high by 8 feet wide , or any other arrangement of linear measurements that yields the same volume. A more unusual measurement for firewood is the "rick" or face cord. It is stacked deep with the other measurements kept the same as a cord, making it of a cord; however, regional variations mean that its precise definition is non-standardized.
Twenty-foot equivalent unit
The twenty-foot equivalent unit is the volume of the smallest standard shipping container. It is equivalent to . Larger intermodal containers are commonly described in multiples of TEU, as are container ship capacities.
Acre-foot