Inches to Millimeters Converter
Convert inches (in) to millimeters (mm), with the formula, a conversion table and exact factors.
Change the values and press Calculate to work out your own figures.
Convert a length from one unit to another. For inches, feet and yards you also get feet and inches with a tape-measure fraction.
Show the working
- 1 in = 25.4 mm
- 1 × 25.4 = 25.4 mm
How to convert inches to millimeters
1 in = 25.4 mm, so multiply by 25.4 to go from inches to millimeters. Going the other way, 1 mm = 0.0393700787402 in.
mm = in × 25.4 in = mm × 0.0393700787402
Worked example:
1 in = 25.4 mm 5 × 25.4 = 127 mm
Inches to millimeters table
| Inches | Millimeters |
|---|---|
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 4 in | 101.6 mm |
| 5 in | 127 mm |
| 6 in | 152.4 mm |
| 7 in | 177.8 mm |
| 8 in | 203.2 mm |
| 9 in | 228.6 mm |
| 10 in | 254 mm |
| 15 in | 381 mm |
| 20 in | 508 mm |
| 25 in | 635 mm |
| 30 in | 762 mm |
| 40 in | 1016 mm |
| 50 in | 1270 mm |
| 75 in | 1905 mm |
| 100 in | 2540 mm |
| 250 in | 6350 mm |
| 500 in | 12700 mm |
| 1000 in | 25400 mm |
About the units
- Inches (in)
- Inches, a US customary unit. Definition: NIST Handbook 44 Appendix C (international yard and pound, 1959).
- Millimeters (mm)
- Millimeters, a metric unit. Definition: BIPM SI Brochure (SI prefixes).