About the mm to mi calculation
One millimeter is exactly 6.2137e-7 miles, so converting between them is a single multiplication. Enter any value above and the result updates as you type. The standard fine unit on engineering drawings and rainfall figures. Road distances in the US and UK. Defined as exactly 1,609.344 metres since 1959.
Formula
mi = mm × 6.2137e-7
1 mm = 6.2137e-7 mi
1 mi = 1,609,344 mmWorked example
To convert 100 mm, multiply by 6.2137e-7: 100 × 6.2137e-7 = 0.00006214 mi.
Frequently asked questions
How many miles are in a millimeter?
There are 6.2137e-7 miles in one millimeter. To convert any amount, multiply the number of millimeters by 6.2137e-7.
How do I convert miles back to millimeters?
Divide instead of multiplying, or equivalently multiply by 1,609,344. One mile is 1,609,344 millimeters.
Is this conversion exact?
Yes. Since the international agreement of 1959, the relationship between millimeters and miles is defined exactly rather than measured, so the only rounding here is in how many decimal places we show.
Where is each of these units used?
Millimeters: the standard fine unit on engineering drawings and rainfall figures. Miles: road distances in the US and UK. Defined as exactly 1,609.344 metres since 1959.
Sources
- NIST Special Publication 811 — Guide for the Use of the International System of Units