The following are typical abbreviations for units of measurement. Most social sciences and related fields use metric units (km, mg), but in other fields and in everyday use, US standard units (mi, lb) are typical. Generally, use abbreviations for units when they appear with numerals; spell out the units when they are used alone or when they are used with spelled-out numbers (see also 41a).
| metric units | us standard units |
| m, cm, mm | yd, ft, in. |
| km, kph | mi, mph |
| kg, g, mg | lb, oz |
Results were measured in pounds.
Runners in the 5-km race had to contend with a stiff headwind.
Use no periods after abbreviations for units of measurement, except the abbreviation for “inch” (in.), to distinguish it from the preposition in.