Speed Converter
Convert speed between km/h, mph, m/s, knots and ft/s instantly. Free and private, right in your browser.
Convert between km/h, mph, m/s, and knots instantly, handy for reading a foreign car's speedometer, converting wind or boat speed from a marine forecast, or plugging a velocity into a physics problem.
How to use it
- Enter a speed value in any one field
- Pick the unit it's in. Km/h, mph, m/s, or knots
- Read the converted value in the other three units instantly
Frequently asked questions
- How accurate is the conversion?
- It uses exact conversion factors (1 mph = 1.609344 km/h, 1 knot = 1.852 km/h exactly), so results are precise to as many decimal places as you need, not rounded estimates.
- What's the difference between a knot and mph?
- A knot is one nautical mile per hour (1.852 km/h), while a mph is one statute mile per hour (1.60934 km/h). Knots run about 15% faster than the same number in mph, which matters if you're reading marine or aviation weather reports against a car speedometer.
- Why would I need m/s instead of km/h?
- m/s is the standard unit in physics problems and engineering specs (e.g. wind speed, fall velocity, projectile motion), so if you're plugging a speed into a formula or a spec sheet, you'll usually want it in m/s rather than km/h or mph.
- 1
Nothing is uploaded
The file never leaves your device. There is no server to send it to, so there is nothing to leak, log, or subpoena.
- 2
No signup, no limits
No account, no email, no daily cap, no watermark, and no paid tier waiting behind the third file.
- 3
Works offline
Load the page once and it keeps working with the network off, because all the work was always happening locally.