Inches to Millimetres Converter
Convert inches to millimetres instantly. Enter any inch value — including fractions as decimals — and see the exact mm result. Used in engineering, woodworking, and precision manufacturing.
Formula:[value] in × 25.4 = [result] mm
How to convert Inches to Millimetres
in × 25.4 = mm
For example: 3 in × 25.4 = 76.2 mm
↑ Use the converter aboveCommon Inches to Millimetres conversions
| Inches (in) | Millimetres (mm) |
|---|---|
| 0.25 in | 6.35 mm |
| 0.5 in | 12.7 mm |
| 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 |
| 8 in | 203.2 mm |
| 10 in | 254 mm |
| 12 in | 304.8 mm |
| 18 in | 457.2 mm |
| 24 in | 609.6 mm |
| 36 in | 914.4 mm |
About this conversion
Inches to millimetres is a precision conversion used daily in engineering, woodworking, plumbing, and manufacturing. Since 1 inch = 25.4 mm exactly, the conversion is always precise. Common fractional inch sizes in mm: 1/32" = 0.794 mm, 1/16" = 1.588 mm, 1/8" = 3.175 mm, 1/4" = 6.35 mm, 3/8" = 9.525 mm, 1/2" = 12.7 mm, 3/4" = 19.05 mm. Thread sizes, drill bits, pipe fittings, and sheet metal gauges are often specified in both inches and millimetres, making this conversion essential for anyone working across imperial and metric tooling.