Conversion formula

The conversion factor from miles per hour to kilometers per hour is 1.6093439999987, which means that 1 mile per hour is equal to 1.6093439999987 kilometers per hour:

1 mph = 1.6093439999987 km/h

To convert 21 miles per hour into kilometers per hour we have to multiply 21 by the conversion factor in order to get the velocity amount from miles per hour to kilometers per hour. We can also form a simple proportion to calculate the result:

1 mph → 1.6093439999987 km/h

21 mph → V_(km/h)

Solve the above proportion to obtain the velocity V in kilometers per hour:

V_(km/h) = 21 mph × 1.6093439999987 km/h

V_(km/h) = 33.796223999973 km/h

The final result is:

21 mph → 33.796223999973 km/h

We conclude that 21 miles per hour is equivalent to 33.796223999973 kilometers per hour:

21 miles per hour = 33.796223999973 kilometers per hour

Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 kilometer per hour is equal to 0.029589104392278 × 21 miles per hour.

Another way is saying that 21 miles per hour is equal to 1 ÷ 0.029589104392278 kilometers per hour.

Approximate result

For practical purposes we can round our final result to an approximate numerical value. We can say that twenty-one miles per hour is approximately thirty-three point seven nine six kilometers per hour:

21 mph ≅ 33.796 km/h

An alternative is also that one kilometer per hour is approximately zero point zero three times twenty-one miles per hour.

Conversion table

miles per hour to kilometers per hour chart

For quick reference purposes, below is the conversion table you can use to convert from miles per hour to kilometers per hour