Driving abroad, reading a weather report, or checking a sailing forecast — sooner or later a speed arrives in the wrong unit. This free speed converter turns one speed into the units you actually need: miles per hour, kilometres per hour, metres per second, knots, and feet per second, all at once. It is a plain calculator, so everything runs in your browser, nothing is uploaded, and no signup is needed.
How to use this speed converter
One number in, every common unit out.
Enter a number and pick the unit it is in — mph, km/h, m/s, knots, or feet per second.
The result shows the same speed converted into all the other units, so you do not have to convert twice.
Copy the value that matches your road sign, forecast, or textbook and carry on — nothing is saved.
Why this speed converter keeps road, sea, and air speeds straight
One tool for the three worlds that each insist on their own unit.
Convert mph to km/h for driving abroad and km/h to mph for US and UK roads, using the exact factor 1 mph = 1.609344 km/h.
A knot is one nautical mile per hour, exactly 1.852 km/h, so sailing and aviation figures convert without guesswork.
Physics and weather figures in m/s convert with the exact relation 1 m/s = 3.6 km/h.
Results show enough decimals to check your own working, and the exact factors are stated so you can verify them.
Reading a foreign speed limit without getting it wrong
The conversions are easy; the mistakes come from mixing the units up.
Multiply mph by 1.60934 for km/h, and km/h by 0.621371 for mph. So 60 mph is 96.56 km/h, and a 100 km/h limit is 62.1 mph. A handy roadside estimate is to multiply km/h by 5 and divide by 8 — 80 km/h reads as about 50 mph — but treat it as an estimate, not the limit, when a fine is at stake.
Knots are not mph. A 20-knot wind is about 23 mph and 37 km/h, not 20 of either. Because a nautical mile is exactly 1,852 metres, 1 knot is exactly 1.852 km/h, and that exact figure is what this tool uses.
Mach is not a fixed speed, so this tool does not pretend it is. Mach 1 is the speed of sound, which changes with temperature and altitude — roughly 1,235 km/h at sea level. If a source quotes Mach without stating the conditions, convert it with caution and say which conditions you assumed.
Speed Converter FAQs
Short, direct answers to the questions readers ask most.
Multiply mph by 1.609344 — so 60 mph is 96.56 km/h. This tool does that multiplication for you and shows the other units too.
One knot is exactly 1.852 km/h, because a knot is one nautical mile per hour and a nautical mile is exactly 1,852 metres.
Multiply m/s by 3.6, so 10 m/s is 36 km/h. Divide km/h by 3.6 to go the other way.
The US and the UK kept miles per hour for road speeds, while most other countries use kilometres per hour. The speed itself is identical — only the unit on the sign differs.
Yes. It runs entirely in your browser — no account, no signup, and nothing uploaded.
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