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INTERNATIONAL SYSTEM OF UNITS (SI)
When a number written in figures is used to express a measurement, the SI (metric) symbol of the unit must follow the figures. If the symbol is not commonly known, the name of the unit may be written in parentheses after the symbol.
Example:
15 µV (microvolts)
SI symbols are printed in accordance with the Canadian Metric Practice Guide.
They are written in lower-case letters (e.g. m for metre) unless the name of the unit is derived from a proper name, in which case the symbol is written in upper case letters (e.g. A for ampere).
They remain unaltered in the plural (i.e. do not add an
"s"
).
They are written without periods (except at the end of a sentence).
They are placed after the numerical value in the expression for a quantity, with a space between the numerical value and the first letter of the symbol.
Example:
32 m not 32m
However, when the first character of the expression is not a letter, there is no space.
Examples:
75o12'45" not 75o 12' 45"
32oC not 32 oC
When a number is expressed in letters or when no number is involved, the name of the metric measure is written out.
Examples:
two metres
The form shall set out the number of kilometres between points A and B.
A single SI unit should be used to designate a quantity.
Example:
7.65 m not 7 m 65 cm
An SI symbol should not be used to start a sentence.
SI symbols are the same in French and English.
|
Quantity |
Name |
Symbol |
|---|---|---|
|
Length |
metre |
m |
|
kilometre |
km |
|
|
centimetre |
cm |
|
|
millimetre |
mm |
|
|
Area |
square metre |
m2 |
|
square kilometre |
km2 |
|
|
square centimetre |
cm2 |
|
|
square millimetre |
mm2 |
|
|
hectare |
ha |
|
|
Volume |
cubic metre |
m3 |
|
cubic decimetre |
dm3 |
|
|
cubic centimetre |
cm3 |
|
|
cubic millimetre |
mm3 |
|
|
litre |
l, L or l * |
|
|
millilitre |
ml, mL or ml |
|
|
Mass |
kilogram |
kg |
|
gram |
g |
|
|
milligram |
mg |
|
|
tonne ** |
t |
|
|
Plane Angle |
degree |
o |
|
minute |
΄ |
|
|
second |
˝ |
|
|
Velocity |
metre per second |
m/s |
|
kilometre per hour |
km/h |
|
|
centimetre per second |
cm/s |
|
|
millimetre per second |
mm/s |
|
|
Pressure |
pascal |
Pa |
|
Temperature |
celsius |
oC |
|
Kelvin |
K |
|
|
Force |
newton |
N |
* These alternatives are mentioned in the Weights and Measures Act, Schedule I, Part IV.
The international symbol for litre is the lowercase l, but the uppercase letter or the italic form of the lowercase l is sometimes used to avoid confusion with the number 1.
** The term "tonne"
is used here to refer to a metric ton,
as opposed to an imperial ton equal to 2,240 pounds.
Note: For additional information on the use of SI symbols, see the publication by the Canadian Standards Association, Canadian Metric Practice Guide, National Standard of Canada CAN/CSA-Z234.1-00. See also the schedules to the Weights and Measures Act, R.S. 1985, c. W-6.
