Kilometer per hour (km/h)

Definition

Kilometers travelled per hour, the metric speed unit for vehicles.

History

The kilometer per hour combines the metric kilometer with the hour, and became the standard speed unit as countries adopted the metric system and built road networks. It equals exactly one thousand meters per hour.

Where it is used

Kilometers per hour is the speed unit on car speedometers and road signs across most of the world.

Typical uses include vehicle speed outside the US, speed limits.

Conversion pages

These pages convert kilometer per hour to or from another unit in speed.

• Mile per hour to kilometer per hour
• Meter per second to kilometer per hour

Other Speed units

• Mile per hour (mph)
• Meter per second (m/s)
• Knot (kn)
• Foot per second (ft/s)

Sources

• NIST HB 44 NIST Handbook 44, Appendix C (Tables of Equivalents — international nautical mile); speeds derived from the exact mile, foot and hour · Dataset reviewed Nov 11, 2026