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 Spelling out numbers).
| 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.
Compounds, concentrations, and other common scientific expressions are typically abbreviated. In scientific writing, abbreviations are usually represented without periods.
mA (milliampere)
NaCl (sodium chloride)
1% wt/vol (one percent weight-to-volume ratio)
15 mg/kg iv (fifteen milligrams per kilogram of body weight administered intravenously)
Whether an abbreviation is capitalized or not depends on convention, so check with your instructor or consult a style guide for the discipline in which you are writing.
Formal scientific reports sometimes present a glossary of all technical terms and abbreviations used in the report, either at the beginning or the end of the report. Frequently, however, readers would be expected to know such abbreviations. Spell out terms on first mention if nontechnical readers are part of your audience.
Exercises:
Abbreviations 1
Abbreviations 2
Related topic:
Capitalizing scientific and technical terms