How to convert millimeters to inches
Useful for small components, tools, fasteners, and product dimensions. Multiply the millimeter value by the exact unit relationship shown below. CalcOS evaluates through the meter so this route and its inverse always share one certified definition.
in = mm × 0.0393700787402
Worked example: 25 mm = 0.984251968504 in.
millimeters to inches conversion table
| millimeter (mm) | inch (in) |
|---|---|
| 1 | 0.0393700787402 |
| 5 | 0.196850393701 |
| 10 | 0.393700787402 |
| 25 | 0.984251968504 |
| 50 | 1.96850393701 |
| 100 | 3.93700787402 |
Definitions and precision
The international inch, foot, yard, and mile are exact consequences of 1 inch = 0.0254 meter. Metric prefixes are exact powers of ten. Results may still display rounded decimals because many inverse relationships are repeating numbers.
Related length conversions
Sources: BIPM SI Brochure and NIST Handbook 44, Appendix C. Also see the complete Length Converter guide.