Inches to Millimeters
Convert inches to millimeters instantly. The relationship is fixed: 1 in = 25.4 mm (and 1 mm = 0.0394 in). To go from inches to millimeters, multiply by 25.4.
For example, 10 in is 254 mm. Length conversions like this come up constantly — measuring height, screen and TV sizes, paper, furniture, and anything bought from a country that uses a different measurement system.
Millimeters (mm)
25.4
1 in = 25.4 mm
ResultFull conversion table
| in | mm |
|---|---|
| 1 | 25.4 |
| 2 | 50.8 |
| 3 | 76.2 |
| 5 | 127 |
| 10 | 254 |
| 15 | 381 |
| 20 | 508 |
| 25 | 635 |
| 30 | 762 |
| 50 | 1,270 |
| 100 | 2,540 |
How to convert inches to millimeters
The formula is: mm = in × 25.4. Take your amount in inches, multiply by 25.4, and you have the result in millimeters. To reverse it, divide by 25.4 (or multiply by 0.0394).
Use the table below for the most common values at a glance, or the calculator for any exact amount.
Frequently asked questions
How many millimeters are in 1 in?
1 in equals 25.4 mm.
How many millimeters is 10 in?
10 in is 254 mm.
What's the formula for inches to millimeters?
Multiply inches by 25.4: mm = in × 25.4.
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