5 miles = 8 kilometres. An easy method of converting between units of distance and speed.

If you know that 5 miles is the same as 8km then you can use this conversion to help you change between miles per hour (mph) and kilometres per hour (kmph). So if you need to convert a speed from mph into kmph, then divide the mph speed by 5 and then multiply this answer by 8. On the contrary, if you need to convert from kmph into mph then divide the speed by 8 and multiply by 5. Let’s look at some examples of converting between different types of speed given in mph and kmph.

Example 1

Convert 35mph into kmph.

So to convert this into kmph divide the speed by 5 and multiply by8:

35 ÷ 5 = 7

7 × 8 = 56 kmph

Example 2

Convert 60mph into kmph.

Like example 1, to convert this into kmph divide the speed by 5 and multiply by8:

60 ÷ 5 = 12

7 × 12 = 84 kmph

Example 3

Change 16 kmph into mph.

This time you need to divide by 8 and multiply by 5 as you are changing the speed into miles per hour:

16 ÷ 8 = 2

2 × 5 = 10 mph

Example 4

Change 104 kmph into mph.

Like example 3, you need to divide by 8 and multiply by 5 as you are changing the speed into miles per hour:

104 ÷ 8 = 13

13 × 5 = 65 mph

Let’s take a look at some harder examples.

Example 5

A car is travelling at a constants speed. It travels 24 miles in 20 minutes. Work out the speed of the car in kilometres per hour.

Firstly you will need to work out the speed of the car in miles per hour.

You know that the car covers 24 miles in 20 minutes. Therefore, it you work out how far the car will go in 60 minutes then you will have the speed of the car in miles per hour. Do this by work out how many times 20 goes into 60:

60 ÷ 20 = 3

24 × 3 = 72 miles.

So the car will cover 72 miles in 60 minutes so the speed of the car is 72 miles per hour.

All you need to do next is convert this into kilometres per hour using the same method shown in examples 1 and 2. Since you need the speed in kilometres per hour then you need to divide by 5 and times by 8.

72 ÷ 5 = 14.4

14.4 × 8 = 115.2 mph.

So the speed of the car is 115.2 miles per hour.

So to summarise; to convert speed from mph to kmph divide by 5 and times by 8 and to convert speed from kmph into mph divide by 8 and times by 5.