This comprehensive conversion chart provides precise measurements for converting between fractional inches, decimal inches, and millimeters. Use it as a reference for woodworking, metalworking, engineering, and any project requiring precise measurements.
How to use this chart: Find your fractional inch measurement in the first column, then read across to find the equivalent decimal inch (second column) and millimeter value (third column). For quick reference, remember that 1 inch equals exactly 25.4 millimeters.
| Fraction (inches) | Decimal (inches) | Millimeters (mm) |
|---|---|---|
| 1/64 | 0.0156 | 0.396 |
| 1/32 | 0.0312 | 0.793 |
| 3/64 | 0.0468 | 1.190 |
| 1/16 | 0.0625 | 1.587 |
| 5/64 | 0.0781 | 1.984 |
| 3/32 | 0.0937 | 2.381 |
| 7/64 | 0.1093 | 2.778 |
| 1/8 | 0.1250 | 3.175 |
| 9/64 | 0.1406 | 3.571 |
| 5/32 | 0.1562 | 3.968 |
| 11/64 | 0.1718 | 4.365 |
| 3/16 | 0.1875 | 4.762 |
| 13/64 | 0.2031 | 5.159 |
| 7/32 | 0.2187 | 5.556 |
| 15/64 | 0.2343 | 5.953 |
| 1/4 | 0.2500 | 6.350 |
| 17/64 | 0.2656 | 6.746 |
| 9/32 | 0.2812 | 7.143 |
| 19/64 | 0.2968 | 7.540 |
| 5/16 | 0.3125 | 7.937 |
| 21/64 | 0.3281 | 8.334 |
| 11/32 | 0.3437 | 8.731 |
| 23/64 | 0.3593 | 9.128 |
| 3/8 | 0.3750 | 9.525 |
| 25/64 | 0.3906 | 9.921 |
| 13/32 | 0.4062 | 10.318 |
| 27/64 | 0.4218 | 10.715 |
| 7/16 | 0.4375 | 11.112 |
| 29/64 | 0.4531 | 11.509 |
| 15/32 | 0.4687 | 11.906 |
| 31/64 | 0.4843 | 12.303 |
| 1/2 | 0.5000 | 12.700 |
| 33/64 | 0.5156 | 13.096 |
| 17/32 | 0.5312 | 13.493 |
| 35/64 | 0.5468 | 13.980 |
| 9/16 | 0.5625 | 14.287 |
| 37/64 | 0.5781 | 14.684 |
| 19/32 | 0.5937 | 15.081 |
| 39/64 | 0.6093 | 15.478 |
| 5/8 | 0.6250 | 15.875 |
| 41/64 | 0.6406 | 16.271 |
| 21/32 | 0.6562 | 16.668 |
| 43/64 | 0.6718 | 17.065 |
| 11/16 | 0.6875 | 17.462 |
| 45/64 | 0.7031 | 17.859 |
| 23/32 | 0.7187 | 18.256 |
| 47/64 | 0.7343 | 18.653 |
| 3/4 | 0.7500 | 19.050 |
| 49/64 | 0.7656 | 19.446 |
| 25/32 | 0.7812 | 19.843 |
| 51/64 | 0.7968 | 20.240 |
| 13/16 | 0.8125 | 20.637 |
| 53/64 | 0.8281 | 21.034 |
| 27/32 | 0.8437 | 21.431 |
| 55/64 | 0.8593 | 21.828 |
| 7/8 | 0.8750 | 22.225 |
| 57/64 | 0.8906 | 22.621 |
| 29/32 | 0.9062 | 23.018 |
| 59/64 | 0.9218 | 23.415 |
| 15/16 | 0.9375 | 23.812 |
| 61/64 | 0.9531 | 24.209 |
| 31/32 | 0.9687 | 24.606 |
| 63/64 | 0.9843 | 25.003 |
| 1 | 1.0000 | 25.400 |
Converting between fractional inches and millimeters is essential in many fields, including engineering, construction, manufacturing, and DIY projects. The formula for conversion is:
Millimeters = Inches × 25.4
For fractional inches, first convert to decimal by dividing the numerator by the denominator, then multiply by 25.4 to get millimeters.
These frequently used conversions are highlighted in the chart for quick reference:
These common measurements are frequently used in hardware sizes, tool specifications, and building materials.
This conversion chart is particularly useful for:
Use our interactive tools to convert and visualize specific measurements:
Millimeters
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