Speed Converter
Convert a speed into mph, km/h, m/s, knots and every other unit at once.
Speed units and definitions
The size of each unit is listed below. Each one follows from the definitions of the length and the time unit it uses.
| Unit | Size of one unit | Definition and source |
|---|---|---|
| Metric (SI) | ||
| km/s (kilometer per second) | 1,000 m/s | NIST SP 811, Chapter 4 |
| m/s (meter per second) | 1 m/s | The SI unit of speed. NIST SP 811, Chapter 4 |
| cm/s (centimeter per second) | 0.01 m/s | NIST SP 811, Chapter 4 |
| km/h (kilometer per hour) | 5/18 m/s (about 0.2777778 m/s) | 1,000 m per hour (divide by 3,600 seconds). NIST SP 811, NIST SP 811, Chapter 5 |
| Knot (based on the nautical mile) | ||
| knot (kn) | 463/900 m/s (about 0.5144444 m/s) | 1 nautical mile (1,852 m) per hour. NIST SP 811, Chapter 5, NIST SP 811 |
| US customary and imperial | ||
| mile per hour (mph) | 0.44704 m/s | 1 international mile (1,609.344 m) per hour. NIST SP 811 |
| foot per second (ft/s) | 0.3048 m/s | 1 international foot (0.3048 m) per second. NIST SP 811 |
The calculator first converts your speed to m/s, then divides by the size of each unit. Calculations use exact fractions, and the only rounding is the one applied when a value is displayed.
Examples
- 60 km/h = about 16.66667 m/s (60 × 1,000 ÷ 3,600)
- 1 m/s = 3.6 km/h (multiply meters per second by 3.6 to get kilometers per hour)
- 1 knot = 1.852 km/h = about 0.5144444 m/s
- 1 mph = about 1.609344 km/h (1 mile = 1,609.344 m)
- 1 ft/s = 0.3048 m/s = 1.09728 km/h
Notes
- You can enter decimals (up to 12 digits before the decimal point and 6 decimal places). Thousands separators such as 1,234.5 are accepted; use a period as the decimal separator.
- A knot is a speed of one nautical mile (1,852 m) per hour. It is used at sea and in the air.
- The mile used here is the international mile (1,609.344 m), and the foot is the international foot (0.3048 m).
- Mach is not included. It is a multiple of the speed of sound, which is not a fixed value because it depends on temperature and other conditions.
- Need to convert a length or a time on its own? Use the Length Converter or the Time Converter.
Sources
The definitions on this page come from the sources below (checked on October 31, 2026). Some values are exact by definition (for example, the mile per hour in meters per second), and a source may list them rounded; the notes in the table say how each value is defined.
- NIST Guide to the SI, Chapter 4: The Two Classes of SI Units and the SI Prefixes
- NIST Special Publication 811, Appendix B.8: Factors for units listed alphabetically
- NIST Guide to the SI, Chapter 5: Units Outside the SI
Frequently asked questions
How many m/s is 60 km/h?
About 16.67 m/s. Divide km/h by 3.6 to get m/s (60 ÷ 3.6 = 16.666…).
How do I convert m/s to km/h?
Multiply by 3.6. For example, 10 m/s is 36 km/h.
How many km/h is 1 knot?
1.852 km/h. A knot is one nautical mile (1,852 m) per hour.
How many km/h is 1 mph?
About 1.609344 km/h. Because a mile is 1,609.344 m, multiply the mph value by 1.609344 to get km/h.