How to convert inches to millimeters
One inch equals 25.4 millimeters. To convert, multiply the number of inches by 25.4:
Mental-math shortcut: Multiply inches by 25.4. Fractions: 1/8 in = 3.175 mm, 1/4 in = 6.35 mm, 1/2 in = 12.7 mm.
Example
Convert 0.5 inches to millimeters: 0.5 in × 25.4 = 12.7 mm.
Inches to Millimeters conversion chart
| Inches (in) | Millimeters (mm) |
|---|---|
| 1/16 | 1.5875 |
| 1/8 | 3.175 |
| 1/4 | 6.35 |
| 3/8 | 9.525 |
| 1/2 | 12.7 |
| 5/8 | 15.875 |
| 3/4 | 19.05 |
| 1 | 25.4 |
| 1.5 | 38.1 |
| 2 | 50.8 |
| 3 | 76.2 |
| 4 | 101.6 |
| 6 | 152.4 |
| 12 | 304.8 |
What is an inch?
An inch (in or ″) is a unit of length in the US customary and imperial systems. Since 1959 it has been defined as exactly 2.54 centimeters. There are 12 inches in a foot, and inches are used for screen sizes, height, rainfall and construction in the United States.
What is a millimeter?
A millimeter (mm) is one thousandth of a meter. It is used for small, precise measurements such as screw and drill-bit sizes, jewelry, rainfall, camera lenses and engineering drawings. There are 10 millimeters in a centimeter and exactly 25.4 millimeters in an inch.
Converting the other way? Use the Millimeters to Inches converter.
Frequently asked questions
How many millimeters is one inch?
One inch is 25.4 millimeters.
How do I convert inches to millimeters?
Multiply the value in inches by 25.4. For example, 0.5 in × 25.4 = 12.7 mm.
What is 1 in in millimeters?
1 in is 25.4 millimeters.
How do I convert millimeters to inches?
Multiply millimeters by 0.03937 (or divide by 25.4). You can also use our Millimeters to Inches converter.
Conversions use the internationally agreed definitions of each unit (for example, 1 inch = 2.54 cm exactly) and are rounded for display. Volume converters use US customary units unless stated otherwise.
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