Quick reference table
Common speed conversions
| From | To |
|---|---|
| 1 km/h | 0.6213711922 mph |
| 1 mph | 1.609344000 km/h |
| 1 m/s | 3.600000000 km/h |
| 1 km/h | 0.2777777778 m/s |
| 1 kn | 1.852000000 km/h |
| 1 mph | 0.44704 m/s |
| 1 kn | 1.150779448 mph |
How to convert speed
Road speeds are shown in km/h or mph depending on the country, science uses meters per second, and ships and aircraft use knots. The speed of light and the speed of sound are included as reference points.
Every speed unit is a fixed multiple of one base unit, the m/s. To convert a value, multiply it by the size of the starting unit and divide by the size of the target unit. For example, to convert km/h to mph, multiply by 0.6213711922. To go the other way, divide by 0.6213711922.
The converter above does this for you and shows the exact formula under the result.
Worked examples
Kilometers per hour to Miles per hour
| Kilometers per hour (km/h) | Miles per hour (mph) |
|---|---|
| 1 km/h | 0.6213711922 mph |
| 2 km/h | 1.242742384 mph |
| 5 km/h | 3.106855961 mph |
| 10 km/h | 6.213711922 mph |
| 25 km/h | 15.53427981 mph |
| 50 km/h | 31.06855961 mph |
| 100 km/h | 62.13711922 mph |
| 1,000 km/h | 621.3711922 mph |
Miles per hour to Kilometers per hour
| Miles per hour (mph) | Kilometers per hour (km/h) |
|---|---|
| 1 mph | 1.609344000 km/h |
| 2 mph | 3.218688000 km/h |
| 5 mph | 8.046720000 km/h |
| 10 mph | 16.09344000 km/h |
| 25 mph | 40.23360000 km/h |
| 50 mph | 80.46720000 km/h |
| 100 mph | 160.9344000 km/h |
| 1,000 mph | 1,609.344000 km/h |
Speed units explained
| Unit | Symbol | Equals |
|---|---|---|
| Meters per second | m/s | 1 m/s = 1 m/s |
| Kilometers per hour | km/h | 1 km/h = 0.277777777778 m/s |
| Miles per hour | mph | 1 mph = 0.44704 m/s |
| Knots | kn | 1 kn = 0.514444444444 m/s |
| Feet per second | ft/s | 1 ft/s = 0.3048 m/s |
| Kilometers per second | km/s | 1 km/s = 1,000 m/s |
| Centimeters per second | cm/s | 1 cm/s = 0.01 m/s |
| Mach (at sea level, 15 °C) | Mach | 1 Mach = 340.294 m/s |
| Speed of light | c | 1 c = 299,792,458 m/s |
Popular conversions: kmh to mph, mph to kmh, knots to km/h, m/s to km/h.
Frequently asked questions
How do I convert km/h to mph?
Divide km/h by 1.609344, or multiply by 0.621371. For example, 100 km/h is about 62.14 mph.
How many km/h is one knot?
One knot is exactly 1.852 km/h, because a nautical mile is 1,852 meters and a knot is one nautical mile per hour.
How fast is Mach 1?
Mach 1 is the speed of sound. It depends on temperature and altitude; at sea level and 15 °C it is about 340.3 m/s (1,225 km/h).
How many mph is 1 km/h?
1 km/h = 0.6213711922 mph, and 1 mph = 1.609344000 km/h.
Does this speed converter work offline?
Yes. After the page has loaded once, all calculations run in your browser, so it keeps working without an internet connection.