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Numerals
In general, spell out one through nine. Use figures for 10 or above and whenever preceding a unit of measure or referring to ages of people, animals, events, or things.
Decimals
If a unit of measure follows the numeral, use the decimal format, not fractions.
1.75 mg (NOT 1 3⁄4 mg)
2.5 kg (NOT 2 1⁄2 kg)
If the value is less than 1, insert a zero before the decimal point.
0.2 g (NOT .2 g)
0.9 mg/kg
Fractions
Ordinals
Ordinals generally express ranking rather than quantity, so spell out first through ninth, and use the numeral for 10th and above. Do not use superscript for ordinals.
Examples:
The fourth patient was admitted in critical condition.
The 12th patient died shortly after his arrival.
When you have a mixture of ordinals below and above nine, use numerals. This is a divergence from AP style.
Example: The 5th and the 12th patients showed similar symptoms.
Percentages
Singular and plural
When the quantity is less than 1, the unit of measure is singular.
Examples:
0.5 gram (NOT grams)
0.2 second (NOT seconds)
Spacing
Insert a space between the numeral and the symbol, except for %, °C, °F, ° (for angles), money symbols, fractions, and inches/feet symbols.
| 25 g | 40 mL | 60 kg |
| 30% | 28.5°C | 4” |
| £250 | CHF 50* | 5 ½ years |
*a space is added because CHF is the abbreviation for the Swiss Franc currency and not a symbol.
Units of measure
Abbreviated units of measure do not have a period, unless they close a sentence.
Examples: 50 mg (NOT 50 mg.) 2 dL (NOT 2 dL.)
This page last reviewed on March 5, 2025