Convert inches to millimeters instantly. Type a value below to see the result, or press Swap direction to convert millimeters back to inches. The tool uses the exact conversion factor, and a quick-reference table is below.
Millimeters
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Conversion formula
Millimeters = inches × 25.4
One inch is exactly 25.4 mm. Half an inch is 12.7 mm.
Quick reference table
| Inches (in) | Millimeters (mm) |
|---|---|
| 0.25 in | 6.35 mm |
| 0.5 in | 12.7 mm |
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 4 in | 101.6 mm |
| 6 in | 152.4 mm |
| 8 in | 203.2 mm |
| 10 in | 254 mm |
| 12 in | 304.8 mm |
Frequently asked questions
How do I convert inches to millimeters?
Millimeters = inches × 25.4
How do I convert millimeters back to inches?
Use the reverse formula, or press Swap direction in the converter above. You can also use our reverse converter.
How many mm is 1/2 inch?
Half an inch is 12.7 mm.
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Conversions use standard factors. Check critical measurements.