mm to inches
Read small dimensions for fittings, fasteners and workshop drawings. Fractional inches are rounded to the nearest 1/64.
Edit either value. Use a decimal point; commas group thousands. Rounding affects display only.
How to convert millimeters to inches
Read small dimensions for fittings, fasteners and workshop drawings. Fractional inches are rounded to the nearest 1/64.
Formula coefficients shown rounded. Calculations use the stored factors before display rounding.
A worked example
For 10 mm, the result is approximately 0.3937007874 in. To go the other way, edit the result above or swap the units.
International feet and miles are used, not historical US survey units.
Where the numbers come from
Factors follow NIST conversion references and documented unit definitions. Read our accuracy and rounding notes.
The table and method describe this page’s original pair. Changing units above does not change this reference section.
| Millimeters (mm) | Inches (in) |
|---|---|
| 1 | 0.03937007874 |
| 2 | 0.07874015748 |
| 5 | 0.1968503937 |
| 10 | 0.3937007874 |
| 20 | 0.7874015748 |
| 25 | 0.9842519685 |
| 50 | 1.968503937 |
| 100 | 3.937007874 |
| 500 | 19.68503937 |
| 1000 | 39.37007874 |