How Speed Converter Works
Meters per second is the base unit here, since it's the SI unit speed is defined in. One kilometer per hour equals 0.277778 m/s, one mile per hour equals 0.44704 m/s, and one knot (a nautical mile per hour) equals 0.514444 m/s. Your input is converted to m/s using its own factor, then that value is divided by each other unit's factor to fill in the rest of the results.
How to Use This Tool
- Enter the speed value you want to convert.
- Choose the unit it's currently measured in — km/h, mph, m/s, knots or ft/s.
- The results box updates live, showing that speed in every other unit.
- Select Reset to clear the field and start again.
Example
Converting 100 km/h: 100 × 0.277778 = 27.7778 m/s, which works out to about 62.14 mph (27.7778 ÷ 0.44704) and roughly 54.0 knots (27.7778 ÷ 0.514444).
Helpful Tips
- Road speed limits use km/h in most of the world and mph in the US and UK — double-check which one a sign or spec sheet is using before comparing numbers.
- Knots are the standard for aviation and marine navigation because they're tied to nautical miles, which relate directly to positions on a map's latitude lines.
Frequently Asked Questions
What's the difference between a knot and a mile per hour?
A knot is one nautical mile per hour (1,852 meters), which is slightly longer than a standard (statute) mile of 1,609.344 meters — so a knot is about 15% faster than the same numeric value in mph.
Why is meters per second the base unit instead of km/h?
Meters per second is the SI (International System of Units) definition of speed, so using it as the base keeps the underlying math consistent and avoids compounding rounding errors across units.
How is feet per second useful?
It's common in physics and engineering contexts, such as describing projectile or wind speeds, where imperial units are standard but per-second precision matters more than per-hour figures.
Can I convert a negative speed?
Speed conversions accept negative numbers mathematically, but negative speed isn't physically meaningful — if you're tracking velocity with direction, treat the sign separately from the converted magnitude.
This tool runs entirely in your browser. Your input is not uploaded to any server.