MM to Inches Converter
Convert millimeters to inches instantly — inches = millimeters ÷ 25.4
1 mm = 0.039 in(inches = millimeters ÷ 25.4)
Millimeters to Inches conversion table
| Millimeters (mm) | Inches (in) |
|---|---|
| 1 | 0.039 |
| 2 | 0.079 |
| 3 | 0.118 |
| 5 | 0.197 |
| 6 | 0.236 |
| 8 | 0.315 |
| 10 | 0.394 |
| 12 | 0.472 |
| 15 | 0.591 |
| 20 | 0.787 |
| 25 | 0.984 |
| 25.4 | 1 |
| 50 | 1.969 |
| 100 | 3.937 |
How it works
Enter a value in millimeters and it is converted to inches using the exact factor: inches = millimeters ÷ 25.4. The conversion also works in reverse — edit either field.
MM to Inches formula
inches = millimeters ÷ 25.4
- mm
- millimeters
- in
- inches
Worked example
- Convert 10 mm to inches
- inches = millimeters ÷ 25.4
10 ÷ 25.4 ≈ 0.394 in — just over 3/8 inch
Good to know
- The conversion factor is exact by definition (international yard and pound agreement, 1959) — rounding only comes from the decimals you keep.
- For the reverse conversion, see the Inches to CM converter below.
Related Calculators
Frequently Asked Questions
How do I convert mm to inches?
Divide millimeters by 25.4 — one inch is exactly 25.4 mm. So 50 mm ≈ 1.97 inches.
How many mm is 1 inch?
Exactly 25.4 millimeters, by the 1959 definition of the inch.
What is 10 mm in fractional inches?
10 mm ≈ 0.3937", which sits between 3/8" (0.375") and 13/32" (0.406"). For wrenches, a 10 mm socket is close to — but not interchangeable with — 3/8".
Why do hardware sizes mix mm and inches?
Metric fasteners and tools are sized in mm while many US parts use fractional inches. Because 25.4 mm = 1", some sizes nearly coincide (19 mm ≈ 3/4") — close enough to confuse, not always close enough to swap safely.