Speed Converter
Convert meters per second, kilometers per hour, miles per hour, knots, feet per second and Mach.
· CalcFlow Editorial
1 km/h = 0.62137119 mph
Approximate: Mach depends on air temperature and altitude. This tool uses the International Standard Atmosphere value at sea level (340.294 m/s), so treat Mach results as approximate.
Results shown are estimates for informational purposes only. Nothing on CalcFlow is financial, tax, legal, or medical advice. Always consult a qualified professional before making important decisions.
Common Speed Conversions
| Kilometers per hour | Miles per hour | Meters per second | Knots | Feet per second | Mach (ISA sea level, 340.294 m/s) |
|---|---|---|---|---|---|
| 1 km/h | 0.62137119 | 0.27777778 | 0.5399568 | 0.91134442 | 0.00081628762 |
| 5 km/h | 3.106856 | 1.3888889 | 2.699784 | 4.5567221 | 0.0040814381 |
| 10 km/h | 6.2137119 | 2.7777778 | 5.399568 | 9.1134442 | 0.0081628762 |
| 20 km/h | 12.427424 | 5.5555556 | 10.799136 | 18.226888 | 0.016325752 |
| 30 km/h | 18.641136 | 8.3333333 | 16.198704 | 27.340332 | 0.024488628 |
| 50 km/h | 31.06856 | 13.888889 | 26.99784 | 45.567221 | 0.040814381 |
| 60 km/h | 37.282272 | 16.666667 | 32.397408 | 54.680665 | 0.048977257 |
| 100 km/h | 62.137119 | 27.777778 | 53.99568 | 91.134442 | 0.081628762 |
| 120 km/h | 74.564543 | 33.333333 | 64.794816 | 109.36133 | 0.097954514 |
Popular Speed Conversions
Formula
m/s = value x factor (1 mph = 0.44704 m/s exactly; 1 knot = 1852/3600 m/s; 1 km/h = 1/3.6 m/s)Understanding Speed Conversion
Speed is distance divided by time, so speed units pair a length unit with a time unit. Road speeds are in kilometers per hour in most countries and miles per hour in the United States and UK. Ships and aircraft use knots, a nautical mile per hour. Mach compares speed with the speed of sound, which changes with temperature, so a fixed sea-level reference is used here.
Tips and Best Practices
- 1To convert km/h to mph multiply by 0.6214; mph to km/h multiply by 1.6093.
- 2To convert m/s to km/h multiply by 3.6.
- 3One knot is about 1.15 mph or 1.852 km/h.
Real-World Example
A speed limit of 100 km/h is 100 x 0.621371 = 62.14 mph. A 20 knot wind is 20 x 1.852 = 37.04 km/h.
Common Mistakes to Avoid
- Dividing by 3.6 when you should multiply (m/s to km/h multiplies, km/h to m/s divides).
- Treating a knot as a unit of distance; it is already per hour, so "knots per hour" is wrong.
- Using Mach 1 as a constant 1,235 km/h; it varies with altitude and temperature.
How to Use
- Pick the unit you have in the left selector and the unit you want in the right selector.
- Type a number in either box; the other box updates instantly.
- Use the swap button to reverse the direction and Copy result to copy the answer.
Frequently Asked Questions
How fast is 100 km/h in mph?
How do I convert m/s to km/h?
How many mph is one knot?
Sources: NIST SP 811 (mile, knot); ISO 2533 International Standard Atmosphere (speed of sound 340.294 m/s at sea level, 15 C).