About Mm to Inches
Heights, screen sizes, paper, timber and running distances are all quoted in whichever system the industry grew up with, so this conversion comes up constantly.
One millimetre is 0.0394 inches, and one inche is 25.4 millimetres. The converter handles decimals and large numbers, and the table underneath lists the values people look up most.
How it works
Every millimetres to inches conversion uses one rule: in = mm × 0.039370079.
- Take the measurement in millimetres.
- Multiply by 0.0393700787 — that is how many inches fit in one millimetre.
- The answer is in inches (in).
The factor is exact (1 inch is defined as 2.54 cm), so the only rounding happens when the result is displayed.
Need the other direction? Use the length converter.
Examples
Three conversions worked through in full:
- 1 mm × 0.0393700787 = 0.0394 in
- 12 mm × 0.0393700787 = 0.472 in
- 100 mm × 0.0393700787 = 3.94 in
The table under the calculator lists the values people look up most, from 1 mm upwards.
Mm to Inches: frequently asked questions
- How do I convert millimetres to inches?
- Divide millimetres by 25.4 to get inches. 10 mm ÷ 25.4 ≈ 0.3937 in.
- How do I convert inches back to millimetres?
- Use the swap button, or apply the reverse factor: in × 25.4 = mm.
- Is the conversion exact?
- Yes. 1 inch is exactly 25.4 mm.