Numbers and Units



For decimals less than one use a leading zero.

0.27 not .27

Figures or Words


For a span of numbers use an en rule, eliding to the fewest number of figures possible.

0–1, 132–6

Do not elide numbers in the group 10 to 19.

13–16, 1213–18.


Provided it is not non-dimensional a value in the text must have its associated unit.


Use a full space between a value and the unit. Separate components of the unit with a thin space.

9.87 m s-1 (9.87\ m\,s$^{-1}$)

A common latex mistake is to include the unit while still in math mode.

$9.87\ m\,s^{-1}$ typesets the unit in italics which is wrong


The degree symbol is printed close up to the scale abbreviation when given.

15 °C (15\ $^{\circ}$C).

In non-technical writing the scale is sometimes omitted in which case the degree symbol is printed close up to the number.

15° (15$^{\circ}$)

Values in Kelvin do not include a degree sign.

27 K (27\ K) not 27 °K

Latitude and Longitude

The degree, minute and second symbols are printed close up to the number.

36° N, 155° 13’ 10” W


Do not use a solidus to indicate 'per'.

9.87 m s-1 (9.87\ m\,s$^{-1}$) not 9.87 m/s