Convert Inch to Millimeter
1 inch equals 25.4 millimeters. Enter a value below to convert instantly.
Formula
Multiply the number of inches by 25.4 to get millimeters.
Step by step
- Start with 1 in.
- Multiply by the conversion factor 25.4.
- 1 × 25.4 = 25.4 mm.
Inch to Millimeter 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 |
| 500 | 12,700 |
| 1,000 | 25,400 |
About the inch
The inch (in) is a Imperial unit of length.
About the millimeter
The millimeter (mm) is a SI unit of length.
Where this conversion is used
Converting inches to millimeters comes up when measuring height, screen sizes, travel distances, fabric, and construction dimensions. Metric and Imperial length units are both in daily use, so quick conversion is often needed when following instructions from another country.
Need the other direction? Convert millimeter to inch →
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Frequently asked questions
How many millimeters are in a inch?
One inch equals 25.4 millimeters.
How do you convert inches to millimeters?
Multiply the number of inches by 25.4 to get millimeters.
What is 1 millimeter in inches?
One millimeter equals 0.039370079 inches.
When would I convert inches to millimeters?
This conversion is common when measuring height, screen sizes, travel distances, fabric, and construction dimensions.
Conversion factors are based on internationally agreed unit definitions. See our methodology and sources for details on how these values are verified.