mm to Inches Converter
25.4 mm = 1 in
Use this free mm to Inches Converter to achieve high-precision measurements for your engineering, design, or DIY projects. Millimeters (mm) are a fundamental unit of the metric system used globally for small-scale precision, while inches are the primary unit in the imperial system for hardware, screen sizes, and industrial standards.
Converting between these two units is essential when working with international blueprints, electronic components, or hardware from different regions. Our tool provides instant, accurate results down to the thousandth of an inch, ensuring your project meets exact specifications.
mm to Inches Formula
Conversion Formula
Inches = Millimeters ÷ 25.4
Millimeters = Inches × 25.4
Standard Constants
1 inch = 25.4 mm
1 mm = 0.03937 inches
How to Convert Millimeters to Inches
The international standard for an inch is exactly 25.4 millimeters. To convert from the metric millimeter to the imperial inch, you simply divide your value by 25.4.
Value (in) = Value (mm) / 25.4For the reverse conversion (inches to millimeters), you multiply the inch value by 25.4. This is the most accurate way to translate measurements between systems.
Value (mm) = Value (in) * 25.4Example: If you have a 10mm bolt and need to know its size in inches, divide 10 by 25.4. This results in approximately 0.394 inches.
Similarly, a 25.4mm object is exactly 1 inch long. For quick mental math, remember that 1/8 of an inch is approximately 3.175mm, and 1/4 inch is exactly 6.35mm.
6.35 mm = 0.25 (1/4) inchesReal-World Uses of mm to Inches Conversion
Precision conversion is vital across technical fields and daily utility.
Engineering
Machinists and engineers convert part tolerances and component sizes between metric and imperial blueprints.
Electronics
PCB design and component footprints often mix mm for board layout and inches for pin pitch (e.g., 0.1 inch).
Design & Printing
Graphic designers convert margin sizes and paper thicknesses (gsm/caliper) for international print standards.
Hardware
DIYers and mechanics use these conversions to find the right socket or wrench size for metric vs. imperial bolts.
Common Millimeters to Inches Conversions
| Millimeters (mm) | Inches (in) |
|---|---|
| 1 mm | 0.04 in |
| 5 mm | 0.2 in |
| 10 mm | 0.39 in |
| 25.4 mm | 1 in |
| 50 mm | 1.97 in |
| 100 mm | 3.94 in |
This mm to Inches Converter provides the precision needed for modern technical projects where even a fraction of a millimeter matters. By using the international standard conversion factor of 25.4, you can confidently translate measurements between metric and imperial systems for everything from industrial engineering to home improvement.