Millimetres to inches
Type a value in either box. 1 mm = 0.03937 in.
Last updated
How to convert
To convert millimetres to inches, divide by 25.4 (or multiply by 0.03937).
in = mm × 0.03937
For example: 10 mm ÷ 25.4 = 0.3937 in.
An inch is defined as exactly 2.54 centimetres (since 1959).
In your head: Divide by 25: 50 mm ≈ 2 in (exactly 1.97 in), about 2% high.
When you’ll need it
Drill bits, screws, pipes and jewellery are sized in millimetres in the UK but often in fractions of an inch in the US: a 6 mm bit is close to 1/4 in, and 12 mm is close to 1/2 in.
Common values
| Millimetres (mm) | Inches (in) |
|---|---|
| 1 mm | 0.0394 in |
| 2 mm | 0.0787 in |
| 3 mm | 0.1181 in |
| 5 mm | 0.1969 in |
| 6 mm | 0.2362 in |
| 8 mm | 0.315 in |
| 10 mm | 0.3937 in |
| 12 mm | 0.4724 in |
| 15 mm | 0.5906 in |
| 20 mm | 0.7874 in |
| 25 mm | 0.9843 in |
| 50 mm | 1.9685 in |
Questions
- How many millimetres make an inch?
- 1 inch is 25.4 millimetres, so 1 millimetre = 0.03937 inches.
- What is the formula to convert millimetres to inches?
- in = mm × 0.03937. An inch is defined as exactly 2.54 centimetres (since 1959).
- What is 10 millimetres in inches?
- 10 millimetres is 0.3937 inches.