Convert millimeters to inches
Converting millimeters to inches is a common length task, whether you are checking a recipe, a spec sheet, a travel distance or a homework problem. Since 1 mm equals 0.0393701 in, the math is a single multiplication — and this page does it for you instantly, with the formula, a table of common values and answers to the questions people ask most.
Exact factor
How to convert millimeters to inches
To convert millimeters to inches, multiply the number of millimeters by 0.0393701. For example, 10 mm × 0.0393701 = 0.393701 in.
in = mm × 0.0393701
- Write down the value in millimeters you want to convert.
- Multiply it by 0.0393701 (the exact mm→in factor).
- The result is your value in inches. Check it below with the converter or the table.
Conversion table
Common values of millimeters and their equivalents in inches:
| mm | in |
|---|---|
| 1 | 0.0393701 |
| 2 | 0.0787402 |
| 3 | 0.11811 |
| 4 | 0.15748 |
| 5 | 0.19685 |
| 10 | 0.393701 |
| 20 | 0.787402 |
| 25 | 0.984252 |
| 50 | 1.9685 |
| 100 | 3.93701 |
| 250 | 9.84252 |
| 500 | 19.685 |
About these units
Millimeter (mm). A millimeter is one thousandth of a meter, the smallest length unit in everyday metric use. It is the standard precision unit in engineering drawings, machining and rainfall measurement.
Inch (in). An inch is a unit of the imperial and US customary systems, legally defined as exactly 25.4 millimeters since 1959. It is used for screen sizes, tools and construction in the United States.
Frequently asked questions
How do I convert millimeters to inches?
To convert millimeters to inches, multiply the number of millimeters by 0.0393701. For example, 10 mm × 0.0393701 = 0.393701 in. Or skip the math: type the value into the converter at the top of this page and the result updates instantly.
How many inches are in 1 millimeter?
1 mm = 0.0393701 in. That is the fixed relationship used by this converter and by international standards.
How many millimeters are in 1 inch?
1 in = 25.4 mm. If you are converting in the opposite direction, use our Inch to Millimeter converter for the dedicated table and FAQ.
Is the millimeters to inches conversion exact?
Yes. Both units are defined by international agreement, so the factor of 0.0393701 is exact. Displayed results are rounded to 6 significant digits only for readability.
What is millimeter used for?
A millimeter is one thousandth of a meter, the smallest length unit in everyday metric use. It is the standard precision unit in engineering drawings, machining and rainfall measurement.