← Unit definitions

Kilometer(km)

The kilometer is a metric length unit equal to 1,000 meters and used for long distances.

Reviewed September 4, 2026

Symbol: km
Quantity: Length
Measurement system: SI
SI classification: Prefixed SI unit
Reference unit: Meter
Exact relationship: 1 km = 1,000 m exactly

Visualizing kilometer

The marked distance represents a length of 1 km. The illustration is conceptual and not drawn to physical scale.

What the kilometer is

The kilometer is the standard metric unit for medium and long distances, used in road travel, geography, and everyday navigation.

Convert Kilometer