Inches to MM Converter
Convert inches to millimeters instantly, and millimeters back to inches. Based on the exact 1 inch = 25.4 mm definition.
Independently verified for accuracy
Calculator by Toolsloft ↗- Result
- 25.4 Millimeters (mm)
- Conversion
- 1 Inches (in) = 25.4 Millimeters (mm)
Convert inches to millimeters and back for hardware, screens, print sizes, and machining where the tolerance is in millimeters. Type the number of inches and read the result in mm. The swap button reverses it.
How this is calculated
The inch is defined as exactly 25.4 millimeters (2.54 centimeters), so inches are multiplied by 25.4 to get millimeters and millimeters are divided by 25.4 to get inches. Results are shown to six decimal places so small measurements stay accurate.
How to use
- Enter the number of inches.
- Keep the direction on inches to mm, or press Swap units for mm to inches.
- Read the result in millimeters.
Examples
- One inch:
1 in = 25.4 mm - A foot in mm:
12 in = 304.8 mm - MM back to inches:
25.4 mm = 1 in
FAQ
- How many mm are in an inch?
- Exactly 25.4 millimeters. That value is the official definition of the inch, so the conversion is precise.
- How do I convert inches to mm?
- Multiply the number of inches by 25.4. For example, 12 inches times 25.4 is 304.8 mm.