Kilometer (km)
A kilometer is exactly 1,000 meters. It is the common metric unit for road, route, and geographic distances.
- Symbol
- km
- System
- Metric
- Meter value
- 1,000 m
- Singular
- kilometer
- Plural
- kilometers
- Aliases
- kilometre, kilometres
What a kilometer measures
The kilo prefix means one thousand, placing the kilometer three decimal orders above the meter. It is close enough to a mile for rough mental comparisons but is the smaller unit.
- One kilometer contains exactly 1,000 meters.
- Five kilometers is a common road-race distance.
- One kilometer is approximately 0.621371 mile.
- One mile is approximately 1.60934 kilometers.
Where kilometers are used
Definition and standardization
The kilometer combines the SI prefix kilo with the meter, producing an exact factor of 1,000.
Its symbol is km, with no space or punctuation between the prefix and unit symbol.
For scientific writing, the kilometer is converted through the meter baseline like other SI multiples.
Tools used to measure kilometers
- Vehicle odometer for traveled road distance
- GPS receiver or mapping app for routes
- Surveying and geospatial instruments for mapped distances
Common mistakes
- Using the nautical-mile factor for a statute mile
- Assuming a kilometer and mile are nearly equal
- Rounding 1.609344 too early in multi-step work
Kilometer questions
How many meters are in a kilometer?
There are exactly 1,000 meters in 1 kilometer.
Is a kilometer longer than a mile?
No. One mile is about 1.609 kilometers, so a mile is longer.
What is a quick kilometers-to-miles estimate?
For a quick estimate, multiply kilometers by 0.62. Use the full factor for accurate work.