Convert millimeter (mm) to inch (in) with a transparent formula and reference values.
| Millimeter | Inch |
|---|---|
| 1 mm | 0.03937007874 in |
| 2 mm | 0.07874015748 in |
| 3 mm | 0.1181102362 in |
| 5 mm | 0.1968503937 in |
| 10 mm | 0.3937007874 in |
| 20 mm | 0.7874015748 in |
| 25 mm | 0.9842519685 in |
| 25.4 mm | 1 in |
| 50 mm | 1.9685039 in |
| 100 mm | 3.9370079 in |
1 mm = 0.0393700787401575 in. in = mm × 0.0393700787401575 The interactive converter uses the same unit registry as this table, so the reference values and calculator stay synchronized.
Millimeter: One thousandth of a meter.
Inch: International inch.
To convert millimeters to inches, divide the millimeter value by 25.4. The relationship is exact because the international inch is defined as exactly 25.4 millimeters.
inches = millimeters ÷ 25.4
Millimeters are common in metric product dimensions, fasteners, machining, electronics and technical drawings, while inches remain common in US specifications. Converting between them helps compare dimensions without changing the underlying measurement.
Short answers to common conversion questions.
There are exactly 25.4 millimeters in one international inch.
Divide the millimeter value by 25.4. For example, 10 mm ÷ 25.4 is about 0.3937 inches.
Yes. The international inch is defined as exactly 0.0254 meter, which is exactly 25.4 millimeters.
The exact relationship often produces a repeating decimal when a whole-number millimeter value is expressed in inches. Choose the precision appropriate for your use case.