Convert Inches to Millimeters
Convert inches to millimeters free and instantly. 1 inch = 25.4 mm. Exact formula, worked example and a handy reference table.
To convert inches to millimeters, multiply by 25.4 (1 inch = 25.4 millimeters). For example, 10 inches = 254 millimeters.
Why convert inches to millimeters?
Both inches and millimeters measure length, so converting between them is a simple multiplication: one inch equals 25.4 millimeters. Type any value into the converter above for an instant answer, or use the formula and reference table below.
Inches to millimeters formula
Millimeters = inches × 25.4
Worked example: 10 inches = 254 millimeters.
Inches to millimeters conversion table
| Inches (in) | Millimeters (mm) |
|---|---|
| 1 | 25.4 |
| 2 | 50.8 |
| 3 | 76.2 |
| 5 | 127 |
| 10 | 254 |
| 20 | 508 |
| 50 | 1,270 |
| 100 | 2,540 |
Inches to Millimeters — frequently asked questions
How many millimeters are in a inch?
One inch equals 25.4 millimeters. To convert any amount, multiply the number of inches by 25.4.
How do you convert inches to millimeters?
Multiply by 25.4: Millimeters = inches × 25.4. For example, 10 inches = 254 millimeters.
How do I convert millimeters back to inches?
Do the reverse conversion — see our millimeters-to-inches converter for the formula and an instant calculator.
Is this inches-to-millimeters converter free?
Yes — it's completely free, instant and runs in your browser with no sign-up. Nothing you type is uploaded.