MM to inches●
Millimetres in. Inches out. Convert small measurements in a moment.
Length
Use a decimal point (2.54), scientific notation (1e3), or feet + inches (5 ft 11 in).
Feet + inches detected. The source unit is set to feet. Swap converts the value to the other unit.
Fractional results are rounded to the nearest 1/16 inch.
Try a value
Pick an example to startThe formula
inches = millimetres ÷ 25.4
Divide the number of millimetres by 25.4 to get inches. To go the other way, multiply by the same number.
A worked example
For 100 mm, divide 100 by 25.4. The result is approximately 3.937008 in.
100 ÷ 25.4 ≈ 3.937008 in
Quick reference
Reference values are rounded to 6 decimal places. Use the converter above for other values or precision.
| Millimetres (mm) | Inches (in) |
|---|---|
| 1 | 0.03937 |
| 2 | 0.07874 |
| 5 | 0.19685 |
| 10 | 0.393701 |
| 12.7 | 0.5 |
| 25.4 | 1 |
| 50 | 1.968504 |
| 100 | 3.937008 |
| 254 | 10 |
All equivalent units
The same value, in every supported unit.
Length conversions
For small parts and photo gear.
Use this conversion for fasteners, thicknesses, lens sizes and printed dimensions. Divide millimetres by 25.4 to get inches. Choose Fractions in the Precision menu if you want results such as 3/16 in for workshop use.
Calculation details & precision
Length conversions use metres as the base unit. The international inch is exactly 0.0254 m; a foot is 12 inches, an international mile is 1,609.344 m, and an international nautical mile is 1,852 m.
Automatic displays up to 12 significant digits. Choose 2, 4 or 6 decimal places in Precision for a shorter result. Displayed results are rounded; very large or small values use scientific notation.
Common questions
How many inches is 10 mm?
10 mm is approximately 0.393701 inches. Divide any millimetre value by 25.4 to get inches.
How many inches are in 6 millimetres?
6 mm is approximately 0.23622 in. The converter can show more significant digits or round to a chosen number of decimal places.