Free Speed Converter
The Speed Converter switches between metres per second, kilometres per hour, miles per hour, feet per second, and knots. Enter a value and every unit updates instantly.
Speed feeds straight into fuel maths — the Fuel Consumption Converter handles mpg and L/100km, and Length covers the distances behind them.
How to use the Speed Converter
- 1 Enter the speed you want to convert.
- 2 Choose the source unit — km/h, mph, m/s, knots or feet per second.
- 3 Read the equivalent in the other units, useful for comparing a speed limit with a wind reading or a boat speed.
- 4 Swap the units to work the other way.
How to Use
Enter a speed, choose the source and target units, and the result appears live. The table lists the value in all supported units.
- Metric, imperial, and nautical speed units
- Live result as you type
- Full conversion table
Frequently asked questions
What exactly is a knot?
One nautical mile per hour, which is 1.852 km/h. A nautical mile is one minute of latitude, so a knot is conveniently tied to the globe — which is why aviation and shipping use it instead of km/h.
Why do scientists use metres per second?
Because it is the coherent SI unit: metres divided by seconds, with no arbitrary scaling factor. That makes it drop straight into physics formulas such as force equals mass times acceleration, where km/h would need a conversion constant first.
How do I convert mph to km/h quickly?
Multiply by 1.609344. A rough mental shortcut is to multiply by 1.6, which is accurate to about half a percent — good enough for reading a speed limit sign, but use the exact factor when the number matters.
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