User:40bus/Manual of Style

General guidelines on use of units

Aspect	Guideline	Acceptable	Unacceptable
Unit names and symbols	Except as listed in the § Specific units table below, unit symbols are uncapi­tal­ized unless they are derived from a proper name, in which case the first letter (of the base unit symbol, not of any prefix) is capitalized.	8 kg 100 kPa	8 Kg 100 kpa
	Unit symbols are undotted.	38 cm of rope	38 cm. of rope 5 km.
	Unit names are given in lower case except: where any word would be capital­ized, or where otherwise specified in the SI brochure or this Manual of Style.	A gallon is 4 quarts. 4 pascals	A Gallon is 4 Quarts. 4 Pascals
		He walked several miles. Miles of trenches were dug.
	The spelling of certain unit names (some of which are listed in § Specific units, below) varies with the variety of English followed by the article.
	Write unit names and symbols in upright (roman) type, except where emphasizing in context.	10 m 29 kilograms	10 m 29 kilograms
		Thus each two-liter jug contained only two quarts.
	Do not use precomposed unit symbol characters.		㎓, ㎦, ㎍, ㎖, ㎉
Numeric values	Do not spell out numbers before unit symbols ...	12 min	twelve min
	... but words or figures may be used with unit names.	twelve minutes 12 minutes
	Use a non-breaking space ({{nbsp}} or  ) between a number and a unit symbol, or use {{nowrap}} ...	29 kg (markup: 29 kg or {{nowrap|29 kg}})	29kg
	... though with certain symbols no space is used (see "Specific units" table below) ...	23° 47′ 22″	23 ° 47 ′ 22 ″
	... and a normal space is used between a number and a unit name.	29 kilograms (markup: 29 kilograms)
	To form a value and a unit name into a compound adjective use a hyphen or hyphens ...	a five-day holiday a five-cubic-foot box a 10-centimeter blade
	... but a non-breaking space (never hyphen) separates a value and unit symbol.	a blade 10 cm long	a 10-cm blade
Plurals	SI unit names are pluralized by adding -s or -es ...	1 ohm; 10 ohms
	... except for these irregular forms.	1 henry; 10 henries 1 hertz; 10 hertz 1 lux; 10 lux 1 siemens; 10 siemens	10 henrys 10 hertzes 10 luxes 10 siemenses
	Some non-SI units have irregular plurals.	1 foot; 10 feet	10 foots
		1 stratum; 10 strata (unusual)	10 stratums
	Unit symbols (in any system) are identical in singular and plural.	grew from 1 in to 2 in grew from 1 inch to 2 inches grew from one to two inches	grew from 1 in to 2 ins
Powers	Format exponents using <sup>, not special characters.	km2 (markup: km<sup>2</sup>)	km² (km&#178;)
	Or use squared or cubed (after the unit being modified).	ten metres per second squared	ten metres per squared second
	For areas or volumes only, square or cubic may be used (before the unit being modified).		ten metres per square second
		tons per square mile
	sq or cu may be used with US customary or imperial units, but not with SI units.	15 sq mi 3 cu ft	15 sq km 3 cu m
Products	Indicate a product of unit names with either a hyphen or a space.	foot-pound foot pound	footpound foot⋅pound
	Indicate a product of unit symbols with &sdot; or &nbsp;.	ms = millisecond m⋅s or m s = metre-second
	Exception: In some topic areas, such as power engineer­ing, certain products take neither space nor &sdot;. Follow the practice of reliable sources in the article's topic area.	Wh, VA, Ah kWh, MVA, GAh
	To pluralize a product of unit names, pluralize only the final unit. (Unit symbols are never pluralized.)	ten foot-pounds	ten feet-pounds
Ratios, rates, densities	Indicate a ratio of unit names with per.	meter per second	meter/second
	Indicate a ratio of unit symbols with a forward slash (/), followed by either a single symbol or a parenthesized product of symbols – do not use multiple slashes. Or use −1, −2, etc.	metre per second m/s m⋅s−1	mps
		kg/(m⋅s) kg⋅m−1⋅s−1	kg/m⋅s kg/m/s
	To pluralize a ratio of unit names, pluralize only the numerator unit. (Unit symbols are never pluralized.)	ten newton-metres per second 10 N⋅m/s
	Some of the special forms used in the imperial and US customary systems are shown here ...	mph = miles per hour mpg = miles per gallon psi = pounds per square inch
	... but only the slash or negative exponent notations are used with SI (and other metric) units.	g/m2 g⋅m−2	gsm
		km/h km⋅h−1	kph
Prefixes	Prefixes should not be separated by a space or hyphen.	kilopascal	kilo pascal kilo-pascal
	Prefixes are added without contraction, except as shown here:	kilohm megohm hectare	kiloohm megaohm hectoare
	The deci-, deca-, and hecto- prefixes should generally be avoided; exceptions include decibel, hectolitre, hectare, and hectopascal.	100 metres 0.1 km	1 hectometre
	Do not use M for 103, MM for 106, or B for 109 (except as noted elsewhere on this page for M and B, e.g. for monetary values)	3 km 8 MW 125 GeV	3 Mm 8 MMW 125 BeV
Mixed units	Mixed units are traditionally used with the imperial and US customary systems ...	a wall 1 ft 1 in thick a wall 1 foot 1 inch thick a man 6 feet 2 inches tall a 6-foot 2-inch man a 6 ft 2 in man	1 ft , 1 in (no comma) 1 foot , 1 inch a man 6 foot 2 tall a 6-foot 2 man
		1 US fl pt 8 oz 1 US fl pt 8 US fl oz
	... and in expressing time durations ...	1:30:07 1:30  1 h 30 min 7 s 01h 30m 07s	1:30′07″ 1:30′ 1 hr 30 min 7 sec 1 h 30 m 7 s
	... but are not used with metric units.	1.33 m 133 cm	1 m 33 cm

Note to table:

Very unacceptable forms

• six kg. thirty g.