Speed Converter
Speed is distance travelled per unit of time. The SI unit is the metre per second (m/s). Road speeds use kilometres per hour or miles per hour, where 1 km/h is exactly 1/3.6 m/s. A knot is one nautical mile — 1,852 metres — per hour, and is standard in aviation and at sea.
1 Kilometer/Hour = 0.6213711922 Mile/Hour
How to convert Kilometer/Hour to Mile/Hour
One Kilometer/Hour equals 0.6213711922 Mile/Hour, so multiply any value in km/h by 0.6213711922 to get mph. To convert back, divide by 0.6213711922 — or multiply by 1.609344.
mph = km/h × 0.6213711922
Example: 25 km/h × 0.6213711922 = 15.53427981 mph.
Watch out: Mach number depends on air temperature. This converter uses 343 m/s, the speed of sound in dry air at about 20 °C; at cruising altitude the real figure is lower.
Kilometer/Hour to Mile/Hour table
| Kilometer/Hour (km/h) | Mile/Hour (mph) |
|---|---|
| 1 | 0.6213711922 |
| 2 | 1.242742384 |
| 3 | 1.864113577 |
| 4 | 2.485484769 |
| 5 | 3.106855961 |
| 10 | 6.213711922 |
| 15 | 9.320567884 |
| 20 | 12.42742384 |
| 25 | 15.53427981 |
| 50 | 31.06855961 |
| 75 | 46.60283942 |
| 100 | 62.13711922 |
| 250 | 155.3427981 |
| 500 | 310.6855961 |
| 1,000 | 621.3711922 |
Mile/Hour to Kilometer/Hour table
| Mile/Hour (mph) | Kilometer/Hour (km/h) |
|---|---|
| 1 | 1.609344 |
| 2 | 3.218688 |
| 3 | 4.828032 |
| 4 | 6.437376 |
| 5 | 8.04672 |
| 10 | 16.09344 |
| 15 | 24.14016 |
| 20 | 32.18688 |
| 25 | 40.2336 |
| 50 | 80.4672 |
| 75 | 120.7008 |
| 100 | 160.9344 |
| 250 | 402.336 |
| 500 | 804.672 |
| 1,000 | 1,609.344 |
Speed units at a glance
All 7 units this converter supports, each expressed in Meter/Second (m/s) and the other way round.
| Unit | Symbol | 1 unit in m/s | 1 m/s in unit |
|---|---|---|---|
| Meter/Second | m/s | 1 | 1 |
| Kilometer/Hour | km/h | 0.2777777778 | 3.6 |
| Mile/Hour | mph | 0.44704 | 2.236936292 |
| Knot | kn | 0.5144444444 | 1.943844492 |
| Foot/Second | ft/s | 0.3048 | 3.280839895 |
| Centimeter/Second | cm/s | 0.01 | 100 |
| Mach | Ma | 343 | 0.002915451895 |
Popular conversions
Where speed conversions are used
Speed limits and road travel, aviation, sailing, athletics and cycling, and wind speed reporting.
Frequently asked questions
What is 1 Kilometer/Hour in Mile/Hour?
1 Kilometer/Hour (km/h) is 0.6213711922 Mile/Hour (mph).
What is 1 Mile/Hour in Kilometer/Hour?
1 Mile/Hour (mph) is 1.609344 Kilometer/Hour (km/h).
How do I convert Kilometer/Hour to Mile/Hour?
Multiply the value in Kilometer/Hour by 0.6213711922. For example, 5 km/h × 0.6213711922 = 3.106855961 mph. To go the other way, divide by 0.6213711922.
How many units does the speed converter support?
It converts between 7 units: Meter/Second, Kilometer/Hour, Mile/Hour, Knot, Foot/Second, Centimeter/Second, Mach.
What should I watch out for when converting speed?
Mach number depends on air temperature. This converter uses 343 m/s, the speed of sound in dry air at about 20 °C; at cruising altitude the real figure is lower.
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Figures on this page are calculated with the same conversion factors as the converter above and shown to up to 10 significant figures. See our disclaimer before relying on a result in a professional or safety-critical context.