Kilometers per hour.
km/h to Kilometer per Seconds Converter — km/h to km/s
Convert km/h (km/h) to Kilometer per Seconds (km/s) using the exact conversion factor (1 km/h = 0.0002777778 kilometer per seconds). See the formula, worked examples, conversion table, history, and common uses.
km/h to Kilometer per Seconds converter
Converter
Speed Converter
Convert road, aviation, marine, lab, and scientific speed units.
Context values
Some unit families need one extra value for a physically accurate result.
Distance divided by time.
Result = input x 0.2777777778 / 1000.
Speed uses meters per second as the base unit.
Reserved above the conversion cards and below the converter.
About Converting km/h to Kilometer per Seconds
km/h and Kilometer per Seconds both describe speed, and the conversion matters whenever a maritime or aviation speed (knots) needs to be compared against a road speed (mph). km/h is most often used for road speed limits and vehicle speedometers outside the us.
Formula
kilometer per seconds = km/h × 0.000277777777778
This factor comes from each unit's defined relationship to the category's base unit: 1 km/h equals 0.277777777778 base units, and 1 kilometer per seconds equals 1000 base units, so dividing one by the other gives the direct km/h-to-kilometer per seconds factor of 0.000277777777778.
Simple example
1 km/h × 0.0002777777778 = 0.0002777778 km/s
1 km/h = 0.0002777778 kilometer per seconds.
Real-world example
10 km/h × 0.0002777777778 = 0.0027777778 km/s
10 km/h = 0.0027777778 kilometer per seconds.
Conversion table
| km/h (km/h) | Kilometer per Seconds (km/s) |
|---|---|
| 1 km/h | 0.0002777778 km/s |
| 5 km/h | 0.0013888889 km/s |
| 10 km/h | 0.0027777778 km/s |
| 25 km/h | 0.0069444444 km/s |
| 50 km/h | 0.0138888889 km/s |
| 100 km/h | 0.0277777778 km/s |
Reverse conversion: Kilometer per Seconds to km/h
0.0002777778 km/s × 3600 = 1.00000008 km/h
0.0002777778 kilometer per seconds = 1.00000008 km/h.
km/h = kilometer per seconds × 3600
Understanding the km/h
km/h (km/h) measures speed. Kilometers per hour follows directly from the kilometer divided by one hour. It is classified as a SI-derived (metric) unit.
Where it's used: Standard road-speed unit worldwide except the US
Uses of the km/h today
- Road speed limits and vehicle speedometers outside the US
- Weather reporting (wind speed) in most countries
History of the km/h
Km/h is a compound unit with no independent origin story — it follows automatically once the kilometer and hour were each standardized, becoming the default speed unit as metric countries motorized through the 20th century.
Historical origin. km/h was not the invention of a single named person; it developed through the process described above.
Understanding the Kilometer per Seconds (km/s)
Distance divided by time.
km/h — sources
- BIPM SI Brochure — Non-SI units accepted for use with SI — Basis for compound metric units like km/h.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many kilometer per seconds are in 1 km/h?
1 km/h equals 0.0002777778 kilometer per seconds, using the exact defined conversion factor rather than an estimate.
How do I convert km/h to kilometer per seconds?
Multiply the km/h value by 0.0002777777778. The converter above does this instantly to whatever precision you set.
How do I convert kilometer per seconds back to km/h?
Use the reverse factor: 1 kilometer per seconds equals 3,600 km/h. You can also use the swap control in the converter above to flip the direction instantly.
What is a km/h?
km/h (km/h) measures speed. Kilometers per hour follows directly from the kilometer divided by one hour. It is classified as a SI-derived (metric) unit.
What is a kilometer per seconds?
Kilometer per Seconds (km/s) is a unit of speed.
Is the km/h to kilometer per seconds conversion exact?
Yes. Both km/h and kilometer per seconds are defined by fixed standards rather than physical artifacts, so the factor of 0.0002777777778 used above is exact to as many digits as you choose to display.
Where is the km/h still used today?
Standard road-speed unit worldwide except the US