Speed Converter
Convert between kilometers per hour, miles per hour, meters per second, feet per second and knots. 100 km/h is 62.14 mph.
Result
100 km/h = 62.1371 mph
In every speed unit
| Unit | Value |
|---|---|
| Meters per second (m/s) | 27.7778 |
| Kilometers per hour (km/h) | 100 |
| Miles per hour (mph) | 62.1371 |
| Knots (kn) | 53.9957 |
| Feet per second (ft/s) | 91.1344 |
How speed units fit together
A speed is a distance divided by a time, so a speed conversion is two ordinary conversions stacked: one for the distance unit and one for the time unit.
Kilometers per hour and miles per hour share the hour, so only the distance changes. A mile is exactly 1.609344 kilometers, which makes 1 mph exactly 1.609344 km/h. Going from km/h to mph you divide by that number: 100 km/h is 62.14 mph and 130 km/h is 80.78 mph.
Meters per second is the SI unit and the one used in physics and engineering. Here both parts change. An hour has 3,600 seconds and a kilometer 1,000 meters, so 1 m/s is exactly 3.6 km/h, and 1 mph is exactly 0.44704 m/s.
The knot is one nautical mile per hour. A nautical mile is exactly 1,852 meters, so a knot is exactly 1.852 km/h, about 1.151 mph. It is the standard unit at sea and in aviation.
The two road-speed pages add a chart in steps of 5, which is how speed limits are posted, and a scale that puts the two speedometers side by side: km/h to mph and mph to km/h.
Speed limits side by side
| km/h | mph |
|---|---|
| 30 | 18.6 |
| 40 | 24.9 |
| 50 | 31.1 |
| 60 | 37.3 |
| 70 | 43.5 |
| 80 | 49.7 |
| 90 | 55.9 |
| 100 | 62.1 |
| 110 | 68.4 |
| 120 | 74.6 |
| 130 | 80.8 |
| mph | km/h |
|---|---|
| 20 | 32.2 |
| 25 | 40.2 |
| 30 | 48.3 |
| 35 | 56.3 |
| 40 | 64.4 |
| 45 | 72.4 |
| 50 | 80.5 |
| 55 | 88.5 |
| 60 | 96.6 |
| 65 | 104.6 |
| 70 | 112.7 |
All speed conversions
Popular questions
How fast is 100 km/h in miles per hour?
62.14 mph. To convert km/h to mph, divide by 1.609344.
How do I convert meters per second to kilometers per hour?
Multiply by 3.6. There are 3,600 seconds in an hour and 1,000 meters in a kilometer, so 10 m/s is 36 km/h.
What is a knot?
One nautical mile per hour: exactly 1.852 km/h, or about 1.1508 mph.
Sources
- NIST Special Publication 811, Guide for the Use of the International System of Units, Appendix B.8: Factors for Units Listed Alphabetically — exact factors are printed in bold in the NIST table (checked October 12, 2026)
- BIPM, The International System of Units (SI Brochure), 9th edition — defines the SI units, the prefixes and the units accepted for use with the SI