Inches to MM Converter
Convert inches (in) to millimeters (mm) instantly. Type a value — the result updates as you type, and the swap button converts the other way.
More mm and inch tools
Inches to mm formula
mm = in × 25.4
1 inch = 25.4 millimeters · 1 millimeter = 0.0394 inches
To convert inches to millimeters, multiply the value by 25.4. For example, 1 in:
mm = 1 × 25.4mm = 25.4
So 1 in = 25.4 mm.
Mental math shortcut
This conversion is exact, so there is no need to estimate: just multiply by 25.4.
Inches to mm conversion table
mm back to Inches
The same values converted the other way, rounded for everyday use:
| Millimeters | Inches |
|---|---|
| 2.54 mm | 0.1 in |
| 3.18 mm | 0.1252 in |
| 6.35 mm | 0.25 in |
| 12.7 mm | 0.5 in |
| 19.05 mm | 0.75 in |
| 25.4 mm | 1 in |
| 38.1 mm | 1.5 in |
| 50.8 mm | 2 in |
About the units
Inches (in)
An inch is defined as exactly 2.54 centimeters. There are 12 inches in a foot; inches are used in the US for screens, heights and small lengths.
Millimeters (mm)
A millimeter is one thousandth of a meter (0.1 cm). It is used for small, precise measurements like rainfall, screws and paper thickness.
Frequently asked questions
How many millimeters are in a inch?
One inch equals 25.4 millimeters.
What is 1 Inches in mm?
1 in = 25.4 mm.
How do I convert mm back to Inches?
Divide the millimeters by 25.4. Or use the MM to Inches converter.