mm to inches
1 millimeter equals 0.03937 inches. Formula: inches = millimeters ÷ 25.4.
= 0.393701 in
Other direction: inches to mm
Formula
inches = millimeters ÷ 25.4
Example: 10 mm = 0.393701 in.
When you need mm to inches
Millimeters dominate technical measurements: engineering drawings, drill bits, jewelry (ring bands, watch cases), camera filters, and rainfall are all specified in mm. When the other half of the project uses imperial tools, dividing by 25.4 bridges the gap — a 10 mm bolt head is about 0.394 inches, which is why a 3/8-inch (0.375 in) wrench almost, but not quite, fits it.
For woodworking and machining you often want fractional inches rather than decimals. Convert to decimal inches first, then multiply by 64 and round to get 64ths: 6 mm → 0.2362 in → about 15/64.
Common mm to in values
| Millimeters (mm) | Inches (in) |
|---|---|
| 1 | 0.03937 |
| 2 | 0.07874 |
| 3 | 0.11811 |
| 5 | 0.19685 |
| 6 | 0.23622 |
| 8 | 0.314961 |
| 10 | 0.393701 |
| 12 | 0.472441 |
| 15 | 0.590551 |
| 20 | 0.787402 |
| 25 | 0.984252 |
| 50 | 1.9685 |
FAQ
What is 10 mm in inches?
10 mm is about 0.3937 inches — just over 3/8 of an inch (0.375 in). One inch is exactly 25.4 mm.
Is mm to inch the same as mm to in or millimeters to inches?
Yes. mm, millimeter, and millimetre are the same unit; inch and in are the same unit. Divide millimeters by 25.4 for all of those searches.
How do I convert mm to fractional inches?
Divide the millimeters by 25.4 to get decimal inches, then multiply by 64 and round to the nearest whole number to get 64ths of an inch. For example, 6 mm = 0.2362 in ≈ 15/64 in.