Fast, accurate, and easy-to-use conversion calculator for all your measurement needs
Quick access to commonly used mm to inch and inch to mm conversions
Learn about these two measurement systems and how they relate
A millimeter is a unit of length in the International System of Units (SI). It equals one thousandth (1/1000) of a meter, the SI base unit of length.
An inch is a unit of length in the imperial and United States customary systems. It's defined as exactly 25.4 millimeters.
The relationship between millimeters and inches is fixed by international agreement.
Quick reference charts for common measurements
| Millimeters (mm) | Inches (decimal) | Inches (fraction) |
|---|---|---|
| 1 mm | 0.0394 in | 1/25 in |
| 2 mm | 0.0787 in | 5/64 in |
| 3 mm | 0.1181 in | 1/8 in |
| 5 mm | 0.1969 in | 3/16 in |
| 10 mm | 0.3937 in | 3/8 in |
| 15 mm | 0.5906 in | 19/32 in |
| 20 mm | 0.7874 in | 25/32 in |
| 25 mm | 0.9843 in | 1 in |
| 30 mm | 1.1811 in | 1-3/16 in |
| 50 mm | 1.9685 in | 2 in |
| 100 mm | 3.9370 in | 3-15/16 in |
| 150 mm | 5.9055 in | 5-7/8 in |
| 200 mm | 7.8740 in | 7-7/8 in |
| 250 mm | 9.8425 in | 9-7/8 in |
| 300 mm | 11.8110 in | 11-13/16 in |
| 500 mm | 19.6850 in | 19-11/16 in |
| 1000 mm | 39.3701 in | 39-3/8 in |
| Inches (in) | Millimeters (mm) |
|---|---|
| 1/16 in | 1.59 mm |
| 1/8 in | 3.18 mm |
| 1/4 in | 6.35 mm |
| 3/8 in | 9.53 mm |
| 1/2 in | 12.7 mm |
| 5/8 in | 15.88 mm |
| 3/4 in | 19.05 mm |
| 7/8 in | 22.23 mm |
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 4 in | 101.6 mm |
| 5 in | 127 mm |
| 6 in | 152.4 mm |
| 7 in | 177.8 mm |
| 8 in | 203.2 mm |
| 9 in | 228.6 mm |
| 10 in | 254 mm |
| 12 in (1 ft) | 304.8 mm |
| 24 in (2 ft) | 609.6 mm |
| 36 in (3 ft) | 914.4 mm |
| Fraction | Decimal (in) | Millimeters (mm) |
|---|---|---|
| 1/64" | 0.0156" | 0.397 mm |
| 1/32" | 0.0313" | 0.794 mm |
| 1/16" | 0.0625" | 1.588 mm |
| 3/32" | 0.0938" | 2.381 mm |
| 1/8" | 0.125" | 3.175 mm |
| 5/32" | 0.1563" | 3.969 mm |
| 3/16" | 0.1875" | 4.763 mm |
| 7/32" | 0.2188" | 5.556 mm |
| 1/4" | 0.25" | 6.35 mm |
| 9/32" | 0.2813" | 7.144 mm |
| 5/16" | 0.3125" | 7.938 mm |
| 11/32" | 0.3438" | 8.731 mm |
| 3/8" | 0.375" | 9.525 mm |
| 13/32" | 0.4063" | 10.319 mm |
| 7/16" | 0.4375" | 11.113 mm |
| 15/32" | 0.4688" | 11.906 mm |
| 1/2" | 0.5" | 12.7 mm |
Real-world uses for mm to inch conversion
Engineers frequently need to convert between metric and imperial measurements, especially when components are sourced internationally.
Construction projects often use plans with mixed units, requiring builders to convert measurements accurately.
Electronic components like displays, connectors, and circuit boards are measured in both millimeters and inches.
Crafters and DIY enthusiasts often need to convert between units when following patterns or instructions from different regions.
