How to convert inches to millimeters
Use the converter above or multiply by the factor: millimeters = inches × 25.4. So 1 in = 25.4 mm. Enter a value in inches and the converter shows the result in millimeters instantly — free, no sign-up.
Worked examples
- 1 in = 25.4 mm
- 10 in = 254.00 mm
- 100 in = 2,540.00 mm
Inches to millimeters conversion table
| Inches (in) | Millimeters (mm) |
|---|---|
| 1 | 25.4 |
| 2 | 50.8 |
| 5 | 127.00 |
| 10 | 254.00 |
| 20 | 508.00 |
| 50 | 1,270.00 |
| 100 | 2,540.00 |
| 500 | 12,700.00 |
| 1000 | 25,400.00 |
Practical use: small parts, jewellery, DIY measurements.
Frequently asked questions
How many mm are in 1 in?
1 in = 25.4 mm.
What is the formula to convert in to mm?
Multiply inches by 25.4.
How do I convert back from mm to in?
1 mm = 0.03937 in.
What is 1 in in mm?
1 in = 25.4 mm.