How to use the Speed Converter
- Type the speed you want to convert.
- Choose the unit you're converting from and the unit you want.
- Read the result instantly. Use the swap button to convert the other way.
- Check the tables below for every unit and common values.
What does this tool do?
Road speeds use km/h or mph, science uses meters per second, and ships and aircraft use knots (nautical miles per hour). One knot is exactly 1.852 km/h.
Why use it?
- Convert speed limits when driving abroad.
- Wind speeds for sailing and flying.
- Physics homework in m/s.
Common speed conversions
Quick reference:
| km/h | mph | m/s |
|---|---|---|
| 30 | 18.6 | 8.33 |
| 50 | 31.1 | 13.89 |
| 80 | 49.7 | 22.22 |
| 100 | 62.1 | 27.78 |
| 120 | 74.6 | 33.33 |
The formula
mph = km/h ÷ 1.609344
m/s = km/h ÷ 3.6
Privacy
The calculation happens instantly in your browser. The numbers you enter are not sent to our servers or saved. There's no account to create and nothing to install.
Frequently asked questions
How do I convert km/h to mph?
Divide by 1.609. 100 km/h is about 62.1 mph, and 50 km/h is about 31 mph. To go from mph to km/h, multiply by 1.609.
Why do ships and planes use knots?
A nautical mile is based on the Earth's shape — it was originally one minute of latitude — which makes distances easy to work with on charts. One knot is one nautical mile per hour, or exactly 1.852 km/h.
Last reviewed by the M2Toolkit team.