Inch to Millimeter
Convert inch to millimeter with the exact factor, a quick reference table and three worked examples. Everything runs in your browser.
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FromInch (in)
ToMillimeter (mm)
25.4mm
mm = in × 25.4Conversion formula
mm = in × 25.4 The conversion factor is 25.4; multiply directly.
Common conversions
| Inch (in) | Millimeter (mm) |
|---|---|
| 1 | 25.4 |
| 2 | 50.8 |
| 5 | 127 |
| 10 | 254 |
| 20 | 508 |
| 50 | 1,270 |
| 100 | 2,540 |
Worked examples
1
1 in = 25.4 mm
2
10 in = 254 mm
3
100 in = 2,540 mm
Frequently asked questions
How many millimeter are in one inch?
One inch equals 25.4 millimeter. Use mm = in × 25.4 for any value.
What is the conversion formula?
The formula is mm = in × 25.4. Here in is the input unit and mm is the output unit.
Is the result rounded?
The calculation uses the standard factor 25.4. Displayed values keep up to six significant digits.
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