Convert millimetres to miles
1 mm = 6.21371e-7 mi
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How many miles are in a millimetre?
One millimetre is 6.21371192e-7 miles. To convert any amount, multiply by 6.21371192e-7. Going the other way, one mile is 1609344 millimetres.
What is the formula to convert mm to mi?
Multiply the millimetre figure by 6.21371192e-7. So mi = mm × 6.21371192e-7. For a quick mental estimate, dividing by about 1609344 gets you close enough for most everyday purposes.
What does a millimetre actually look like?
One millimetre is roughly the thickness of a credit card, which is 0.76 mm. The millimetre is the working unit of engineering drawings and machining tolerances almost everywhere metric is used, because it avoids decimals for most part dimensions.
And what is a mile?
One mile is a comfortable 20-minute walk. The statute mile is exactly 1,609.344 metres, a consequence of the inch being fixed at 25.4 mm in 1959. It remains the road unit in the US and UK.
Is this conversion exact?
Yes. Since the 1959 international yard and pound agreement, the imperial and metric systems are related by exact definitions rather than measurements — the inch is exactly 25.4 mm and the pound exactly 0.45359237 kg. Everything derived from those, including this conversion, is therefore exact. Round at the end rather than partway through, since rounding mm before converting introduces an error the conversion then multiplies.
About mm to mi
How to convert millimetres to miles
Multiply by 6.21371192e-7. One millimetre is 6.21371192e-7 miles, and one mile is 1609344 millimetres.
mi = mm × 6.21371192e-7
Worked example
10 mm = 0.000006213712 mi. For a sense of scale, one millimetre is roughly the thickness of a credit card, which is 0.76 mm, and one mile is a comfortable 20-minute walk.
About the millimetre
The millimetre is the working unit of engineering drawings and machining tolerances almost everywhere metric is used, because it avoids decimals for most part dimensions.
About the mile
The statute mile is exactly 1,609.344 metres, a consequence of the inch being fixed at 25.4 mm in 1959. It remains the road unit in the US and UK.
Quick reference
| millimetres | miles |
|---|---|
| 1 mm | 6.21371e-7 mi |
| 2 mm | 0.00000124274 mi |
| 5 mm | 0.00000310686 mi |
| 10 mm | 0.00000621371 mi |
| 25 mm | 0.0000155343 mi |
| 50 mm | 0.0000310686 mi |
| 100 mm | 0.0000621371 mi |
| 1000 mm | 0.000621371 mi |
Getting it right
This conversion is exact by definition, so the only limit on accuracy is how many digits you keep. Round at the end rather than partway through — rounding mm to a whole number before converting introduces an error that the conversion then multiplies.
Other length conversions
Convert miles back to millimetres, or pick any other pair with the full unit converter. Related: mm to km, mm to m, mm to cm.