Converte
Length
Everything passes through the metre. The inch is the international inch, 25.4 mm.
How it works
A kilometre is 1000 metres. An international mile is 1609.344 metres. The foot and the yard follow the same inch: 0.3048 m and 0.9144 m.
The screen rounds the result. The factor itself is exact enough that 1 km should come back as 1000 m.
Questions
Which mile?
The international mile, not the nautical mile. Knots are on the speed page.
Is a fabric inch different?
Not here. 1 in = 2.54 cm.
Why not 1.6 km per mile?
1.6 is a road approximation. The international mile is defined as 1609.344 m.