MM to Inches Converter
Convert millimeters to inches and inches to millimeters instantly.
Quick Reference: Millimeters to Inches
| Millimeters (mm) | Inches (in) |
|---|---|
| 1 mm | 0.0394 in |
| 5 mm | 0.1969 in |
| 10 mm | 0.3937 in |
| 25 mm | 0.9843 in |
| 50 mm | 1.9685 in |
| 100 mm | 3.9370 in |
Millimeters to Inches Formula
The conversion between millimeters and inches is based on an exact, internationally agreed definition: 1 inch = 25.4 mm exactly. Since 1959, the inch has been defined relative to the meter, making this conversion precise rather than approximate.
- Millimeters to inches: inches = millimeters ÷ 25.4
- Inches to millimeters: millimeters = inches × 25.4
Common Uses
Converting between millimeters and inches is essential whenever metric and imperial measurements meet. Typical situations include:
- Engineering and manufacturing, where technical drawings may use either system.
- Woodworking, metalworking, and 3D printing with mixed-unit tools and materials.
- Buying hardware such as screws, bolts, and pipes specified in one system.
- Sizing screens, photo prints, and paper between metric and imperial standards.
- Jewelry, watchmaking, and other precision crafts requiring fine measurements.
Note: All conversions use the exact factor 1 inch = 25.4 mm, as defined by the international yard and pound agreement of 1959 and maintained by NIST and BIPM.