Convert Inches to Millimeters
1 in = 25.4 mm. Enter any value below.
Converted to every unit
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Inches to Millimeters formula
mm = in × 25.4
An inch is exactly 2.54 centimeters; there are 12 inches in a foot. A millimeter is one thousandth of a meter, used for small, precise measurements.
Worked example
To convert 5 in, multiply by 25.4: 5 in × 25.4 = 127 mm.
Inches to Millimeters conversion table
| Inches | Millimeters |
|---|---|
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 4 in | 101.6 mm |
| 5 in | 127 mm |
| 6 in | 152.4 mm |
| 7 in | 177.8 mm |
| 8 in | 203.2 mm |
| 9 in | 228.6 mm |
| 10 in | 254 mm |
| 12 in | 304.8 mm |
| 15 in | 381 mm |
| 20 in | 508 mm |
| 25 in | 635 mm |
| 30 in | 762 mm |
| 40 in | 1,016 mm |
| 50 in | 1,270 mm |
| 75 in | 1,905 mm |
| 100 in | 2,540 mm |
| 250 in | 6,350 mm |
| 500 in | 12,700 mm |
| 1,000 in | 25,400 mm |
Frequently asked questions
How many millimeters are in an inch?
1 in equals 25.4 mm.
How do I convert inches to millimeters?
Use the formula mm = in × 25.4. For example, 5 in = 127 mm.
Last reviewed: October 2026 · Uses exact, internationally defined conversion factors.