Speed Converter
Convert km/h to mph, mph to knots, metres per second to anything — and see running speeds as a pace per kilometre and per mile.
Fill in the fields to see your result.
Quick reference table
Everyday speeds converted between the two units you've selected.
The two conversions you'll use
The km/h to m/s one is the most elegant: just divide by 3.6. That's because there are 3,600 seconds in an hour and 1,000 metres in a kilometre, so the whole conversion collapses to a single division. It's worth memorising if you ever deal with physics homework.
Driving abroad
The speed limits you'll actually meet, in both units:
| km/h | mph | Typically |
|---|---|---|
| 30 | 19 | Residential streets, school zones |
| 50 | 31 | Urban default across most of Europe |
| 80 | 50 | Rural roads |
| 100 | 62 | Dual carriageway |
| 120 | 75 | Motorway, much of Europe |
| 130 | 81 | French autoroute |
The mental shortcut for km/h to mph is the same one that works for distance: halve it and add a quarter of the half. 120 becomes 60, plus 15, which is 75. Exactly right.
Knots, and why aviation and shipping kept them
A knot is one nautical mile per hour, and a nautical mile is one minute of latitude. That relationship is the whole reason the unit survives: if you're travelling at 60 knots for an hour, you have moved exactly one degree of latitude. On a paper chart that makes navigation arithmetic almost trivial, and the convention stuck long after the charts went digital.
The name is literal. Sailors measured speed by throwing a log overboard on a rope knotted at regular intervals, then counting how many knots ran out in a set time.
Running pace
Runners don't think in speed, they think in pace — minutes per kilometre or per mile. Enter any running speed above and you'll get both. For reference:
- 10 km/h = 6:00 per km = 9:39 per mile. A steady jog.
- 12 km/h = 5:00 per km = 8:03 per mile. A solid tempo pace.
- 15 km/h = 4:00 per km = 6:26 per mile. Fast club runner.
- 20 km/h = 3:00 per km = 4:49 per mile. Elite marathon pace.
Frequently asked questions
How do I convert km/h to mph in my head?
Halve the number, then add a quarter of that half. 120 km/h: halve to 60, add 15, get 75 mph — which is exact. It works because the true multiplier is 0.621 and a half plus a quarter of a half is 0.625.
Why is 100 km/h not 60 mph?
It's 62.1 mph. The common shorthand of treating 100 km/h as 60 mph is about 3% low, which is close enough for a rough sense of speed and not close enough for a speed limit. The table above gives the real figures for every limit you're likely to meet.
What exactly is a knot?
One nautical mile per hour, which is 1.852 km/h. It survives in shipping and aviation because a nautical mile equals one minute of latitude, so speed in knots translates directly into position on a chart. The name comes from counting knots in a rope paid out behind a ship.
How do I turn my running speed into a pace?
Enter the speed above and the pace appears at the top of the results, in both minutes per kilometre and minutes per mile. The maths is 60 divided by your speed in km/h — so 12 km/h gives 5 minutes per kilometre.
Why is km/h divided by 3.6 to get m/s?
Because an hour is 3,600 seconds and a kilometre is 1,000 metres, so the conversion is 1000/3600, which simplifies to dividing by 3.6. It's the tidiest conversion in this whole category.
Are my numbers sent anywhere?
No. Everything is worked out inside your own browser. Nothing you type is uploaded, stored or shared, and there's no sign-up.
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Please note: CalcuLane uses the internationally agreed definitions, which are exact for length, weight, temperature, volume, speed and data. Shoe sizing is a convention rather than a measurement and varies between brands, so treat those results as a starting point. Where precision genuinely matters, confirm against an authoritative source.