Kilometers per Hour to Miles per Hour Converter

What is a km/h to mph converter?

A kilometers per hour (km/h) to miles per hour (mph) converter changes a speed expressed in the metric unit used by most of the world into the imperial unit used on road signs in the United States and the United Kingdom. Enter a value in either field and the matching speed appears immediately, so you never have to do the arithmetic by hand.

Formula

One mile equals exactly 1.609344 kilometers, so dividing by that factor converts kilometers to miles:

$v_{mph} = \frac{v_{km/h}}{1.609344} = v_{km/h} \times 0.621371$

To go the other way, multiply by 1.609344:

$v_{km/h} = v_{mph} \times 1.609344$

How to convert km/h to mph

1. Take your speed in kilometers per hour.
2. Multiply it by the base factor 0.621371 (equivalently, divide by 1.609344).
3. The result is the same speed expressed in miles per hour.

The single-unit base factor is: 1 km/h = 0.621371 mph.

Worked examples

• 1 km/h to mph: 1 × 0.621371 = 0.621371 mph.
• 60 mph to km/h: 60 × 1.609344 = 96.56064 km/h. This is the common 60 mph highway speed expressed in metric units.
• 100 km/h to mph: 100 × 0.621371 = 62.1371 mph, a typical motorway limit.

FAQ

Is 100 km/h faster than 60 mph? Yes. 100 km/h is about 62.14 mph, so it is slightly faster than 60 mph (which equals roughly 96.56 km/h).

Why is the factor 0.621371 instead of a round number? Because the mile and the kilometer were defined independently. One mile is exactly 1.609344 km, and the reciprocal of that value is the irrational-looking 0.621371 used to convert km/h into mph.