Driver tools Speed converter (mph to kmh)

  • Free speed conversion tool
  • Mph to kmh speed converter
  • Kmh to mph speed converter
  • Why your speedometer isn't always as accurate as the best sat navs

Convert your speed


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Convert miles/h to km/h
Miles per hourKilometers per hour

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This free speed conversion tool lets you convert miles per hour (mph) to kilometres per hour (kmh) and back again.

To get started, just choose whether you want to convert from mph to kmh or from kmh to mph. Then enter the speed you want to convert from and hit calculate.

The speed converter is particularly useful if you're thinking of travelling by car in Europe, where speed limits are generally given in kmh, rather than mph. 

It's always sensible to familiarise yourself with how to convert kmh to mph before you go, especially if you plan to drive your own car, where the speedo will emphasise mph.

Guide to European speed limits

In built-up areas of Europe, speed limits for cars are generally set at 50kmh (31mph) or 60kmh (37mph). This varies from country to country – and even town to town – so make sure you look out for road signs.

On major out-of-town roads, including dual carriageways, the speed limits in Europe increase to anything from 90kmh (55mph) to 120kmh (74mph), depending on both the law and the road.

Motorway limits in Europe also vary widely, with several countries allowing speeds of up to 130kmh (80mph).

Our advice is to check the speed limits of the roads you will be travelling on before you set off.

On a more nerdy point, have you ever wondered why the traditional 0-60mph acceleration times are now usually shown as 0-62mph times? It's because manufacturers measure acceleration in kmh – and 100kmh equals 62mph, as you will see from our speed converter.

Speedometer vs sat nav

The speed shown on your sat nav may be more accurate than the speedometer

Sat navs are more accurate than speedometers

You may notice – particularly when driving quickly – that the speed quoted by your sat nav is lower than the figure displayed on your speedometer. This happens for several reasons.

Firstly, speedometers are not completely accurate. 

Most carmakers set speedometers so they show the vehicle travelling slightly faster than it actually is (up to a limit of around 10%) and other factors, such as tyre condition and the configuration of the car’s gears, can also affect accuracy. 

The latest sat navs are constantly triangulated by satellites, and are almost always detached from the physical workings of the car. 

This means the speed is more accurately monitored (without deliberately leaving room for error) and there are fewer external factors affecting its accuracy.

So, if you want to know your ‘true’ speed, use your sat nav. But if you want to make sure you don't accidentally exceed the speed limit, you are better off following your speedometer.

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