kilometre, km

On this page

• Spelling: “kilometre” or “kilometer”
• Symbol “km”
• Spacing with “kilometre” or “km”
• Use of “kilometre” or “km” in different contexts
• Use of “kilometre” or “km” as a modifier
• Informal use of symbol “K” for “kilometres”
• Additional information

Spelling: “kilometre” or “kilometer”

Canadians generally prefer the British spelling kilometre. However, the American spelling kilometer is also accepted.

Symbol “km”

Because the metric system uses symbols, not abbreviations, the symbol km for kilometre does not contain periods, or an s in the plural form.

• From Winnipeg, it is 2,306 km to Vancouver and 2,372 km to Montréal.

The symbol km is always in lower case, even when the rest of the text is in upper case, as in a newspaper headline.

• Headline: ALBERTA ADDS 10 km OF NEW HIGHWAY IN BANFF

A measurement in kilometres per hour is expressed as km/h (not kmh or kph).

• A good cyclist can travel at 25 km/h for hours on end.

Area and volume in the metric system are expressed by means of superscript numerals: km² (not square kilometres).

• Located east of Yellowknife, Nahanni National Park spans more than 30,000 km².

Spacing with “kilometre” or “km”

Leave a space between kilometre (or its symbol km) and the number or numeral immediately before it.

• It is two kilometres from here to the lake.
• The diameter of the earth is 12,742 km from pole to pole.

Use of “kilometre” or “km” in different contexts

In general writing, for greater clarity, you may use the word kilometres spelled out in full, even after a numeral:

• Matthew received a ticket for driving 55 kilometres per hour in a school zone.

However, in scientific and technical writing, use the symbol km after a numeral:

• The distance from the earth to the moon is 384,400 km.

When no specific figure is stated, write kilometre in full.

• The first bolts of lightning struck near the lake—just a kilometre away.

Use of “kilometre” or “km” as a modifier

For the sake of clarity, when using kilometre as a modifier, insert a hyphen between the numeral and the unit name.

• In this 10-kilometre race, participants may run, walk or bicycle.

However, if you use the symbol km, don’t put a hyphen between the numeral and the symbol.

• In this 10 km race, participants may run, walk or bicycle.

Informal use of symbol “K” for “kilometres”

K isn’t an official symbol for kilometres, but races are often described by this letter. Don’t leave a space or put a hyphen between the numeral and the symbol K.

• Juanita ran a 10K (or a 10 km) race in her best time yet.

Additional information

• Abbreviations: International System of Units (SI)
• Capitalization: SI/metric units