Inch to Millimetre
Free instant inch to millimetre converter. 1 in = 25.4 mm.
Common Inch to Millimetre values
| Inch (in) | Millimetre (mm) |
|---|---|
| 1 | 25.4 |
| 5 | 127 |
| 10 | 254 |
| 25 | 635 |
| 50 | 1270 |
| 100 | 2540 |
| 500 | 12700 |
| 1000 | 25400 |
How does Inch to Millimetre conversion work?
Type a value in the Inch (in) field and the equivalent in Millimetre (mm) appears instantly to the right. The math uses the exact formula shown above — no rounding errors, no approximations beyond standard floating-point precision. Use the swap button to flip the units and see the inverse conversion.
Inch. One twelfth of a foot. About the width of a thumb. Standard for screen sizes, paper, and precision measurement in the US.
Millimetre. One thousandth of a metre. About the thickness of a credit card. Standard in engineering and woodworking.
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No submit button — the result updates as you type. Math runs entirely in your browser, so it’s as fast as your device.
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Works in any modern browser — Mac, Windows, Linux, iPhone, Android, tablets. No installation, no signup.
🎯 Accurate conversions
Conversion factors come from the official standard (NIST, BIPM, ISO definitions where applicable). Values are precise to standard floating-point limits.
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