Inches to MM Converter
Convert inches — including fractional sizes — to millimeters. Enter a decimal value below, or use the chart for common fractions of an inch.
Formula: mm = inches × 25.4
Common inches to millimeters conversions
| Inches | Millimeters |
|---|---|
| 0.0625 in | 1.5875 mm |
| 0.125 in | 3.175 mm |
| 0.25 in | 6.35 mm |
| 0.375 in | 9.525 mm |
| 0.5 in | 12.7 mm |
| 0.75 in | 19.05 mm |
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 6 in | 152.4 mm |
| 12 in | 304.8 mm |
Need the other direction? Convert millimeters to inches or use the full Unit Converter for length, weight, temperature, area, volume and speed.
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How to use inches to mm converter
- 1Enter a length in inches as a decimal (for example 0.25 for 1/4 in).
- 2The equivalent in millimeters appears instantly.
- 3Use the swap button to convert millimeters to inches instead.
- 4Check the chart for the common fractional sizes.
About this tool
One inch is exactly 25.4 mm, so mm = inches × 25.4. Fractions convert the same way once written as decimals: 1/16 in = 1.5875 mm, 1/8 in = 3.175 mm, 1/4 in = 6.35 mm, 1/2 in = 12.7 mm and 3/4 in = 19.05 mm.
Example: a 1/4-inch drill bit is 6.35 mm, so the nearest metric bit is 6.5 mm. This conversion is common when matching US hardware, pipe or tool sizes to metric parts, or reading a pattern written in the other system.
Frequently asked questions
Exactly 25.4 mm.