MM to Inches Converter
Common for wrench and drill sizes, screws, rainfall totals and engineering drawings.
1 mm = 0.03937 in
inches
1 mm = 0.03937 in
How to convert millimeters to inches
Divide the number of millimeters by 25.4.
Formula
in = mm ÷ 25.4
For a quick estimate, multiply by about 0.039370.
Examples
- 3 mm ÷ 25.4 = 0.1181 in
- 10 mm ÷ 25.4 = 0.3937 in
- 25 mm ÷ 25.4 = 0.9843 in
Millimeters to inches conversion table
| Millimeters (mm) | Inches (in) |
|---|---|
| 1 | 0.03937 |
| 2 | 0.07874 |
| 3 | 0.1181 |
| 4 | 0.1575 |
| 5 | 0.1969 |
| 6 | 0.2362 |
| 8 | 0.315 |
| 10 | 0.3937 |
| 12 | 0.4724 |
| 13 | 0.5118 |
| 15 | 0.5906 |
| 19 | 0.748 |
| 20 | 0.7874 |
| 25 | 0.9843 |
| 50 | 1.9685 |
| 100 | 3.937 |
Values rounded to 4 decimal places or 4 significant digits.
About millimeters
The millimeter is one thousandth of a meter. It is the standard unit on engineering and architectural drawings, and it is used for small, precise dimensions such as screw diameters, rainfall totals and the thickness of a phone.
About inches
The inch has been defined as exactly 2.54 centimeters since the 1959 international yard and pound agreement. It is used worldwide for screen sizes and wheel diameters, and in the US for most short measurements.
Frequently asked questions
How many inches are in one millimeter?
One millimeter equals 0.03937 inches (rounded).
How do I convert millimeters to inches?
Divide the number of millimeters by 25.4. For example: 10 mm ÷ 25.4 = 0.3937 in.
How many millimeters are in one inch?
One inch equals 25.4 millimeters.
Is the mm to in conversion exact?
Yes. The factor follows directly from the official definitions of both units, so the only rounding is in how many decimals are displayed.