How it works
An inch is exactly 25.4 millimeters. To convert mm to inches, divide by 25.4. To convert inches to mm, multiply by 25.4.
in = mm ÷ 25.4 · mm = in × 25.4
Tape measures and wrenches use fractions, so the converter also rounds to the nearest 1/16 and 1/32 inch.
Millimeters to inches chart
| Millimeters | Inches |
|---|---|
| 1 mm | 0.0394 in |
| 2 mm | 0.0787 in |
| 3 mm | 0.1181 in |
| 4 mm | 0.1575 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 |
| 25.4 mm | 1 in |
| 30 mm | 1.1811 in |
| 50 mm | 1.9685 in |
| 100 mm | 3.937 in |
Worked example
10 mm ÷ 25.4 = 0.3937 in, about 25/64 (nearest 1/16: 3/8). 3/4 inch (0.75 in) × 25.4 = 19.05 mm.
Frequently asked questions
How many mm in an inch?
Exactly 25.4 millimeters.
How do I convert mm to inches?
Divide by 25.4. For example, 50 mm ÷ 25.4 = 1.9685 inches.
What is 10 mm in inches?
0.3937 inches, a little over 3/8 inch.
What size is 1/4 inch in mm?
6.35 mm. 1/2 inch is 12.7 mm.