If you need to do a quicky conversion and dont have google in front of you, just remember 1.6 and remember kms are always a higher number than miles.

Use the calculator on your phone or watch... and you can go convert-crazy...

20miles x 1.6 = 32kms
(you multiply because the kms will always be a bigger number)


20kms / 1.6 = 12.5miles
(you divide because the miles will always be a smaller number)

Its not perfect to the fraction of the mile or kilometre, but its pretty close.