Decimal / Fraction / mm Converter
Type in any field and the other two update instantly. Fractions are rounded to the nearest 1/64" and reduced to lowest terms. Includes a full reference table of all fractions from 1/64" to 1".
Last updated April 2026
| Fraction | Decimal (in) | Millimeters |
|---|---|---|
| 1/64" | 0.0156" | 0.397 mm |
| 1/32" | 0.0313" | 0.794 mm |
| 3/64" | 0.0469" | 1.191 mm |
| 1/16" | 0.0625" | 1.587 mm |
| 5/64" | 0.0781" | 1.984 mm |
| 3/32" | 0.0938" | 2.381 mm |
| 7/64" | 0.1094" | 2.778 mm |
| 1/8" | 0.1250" | 3.175 mm |
| 9/64" | 0.1406" | 3.572 mm |
| 5/32" | 0.1563" | 3.969 mm |
| 11/64" | 0.1719" | 4.366 mm |
| 3/16" | 0.1875" | 4.762 mm |
| 13/64" | 0.2031" | 5.159 mm |
| 7/32" | 0.2188" | 5.556 mm |
| 15/64" | 0.2344" | 5.953 mm |
| 1/4" | 0.2500" | 6.350 mm |
| 17/64" | 0.2656" | 6.747 mm |
| 9/32" | 0.2813" | 7.144 mm |
| 19/64" | 0.2969" | 7.541 mm |
| 5/16" | 0.3125" | 7.938 mm |
| 21/64" | 0.3281" | 8.334 mm |
| 11/32" | 0.3438" | 8.731 mm |
| 23/64" | 0.3594" | 9.128 mm |
| 3/8" | 0.3750" | 9.525 mm |
| 25/64" | 0.3906" | 9.922 mm |
| 13/32" | 0.4063" | 10.319 mm |
| 27/64" | 0.4219" | 10.716 mm |
| 7/16" | 0.4375" | 11.112 mm |
| 29/64" | 0.4531" | 11.509 mm |
| 15/32" | 0.4688" | 11.906 mm |
| 31/64" | 0.4844" | 12.303 mm |
| 1/2" | 0.5000" | 12.700 mm |
| 33/64" | 0.5156" | 13.097 mm |
| 17/32" | 0.5313" | 13.494 mm |
| 35/64" | 0.5469" | 13.891 mm |
| 9/16" | 0.5625" | 14.287 mm |
| 37/64" | 0.5781" | 14.684 mm |
| 19/32" | 0.5938" | 15.081 mm |
| 39/64" | 0.6094" | 15.478 mm |
| 5/8" | 0.6250" | 15.875 mm |
| 41/64" | 0.6406" | 16.272 mm |
| 21/32" | 0.6563" | 16.669 mm |
| 43/64" | 0.6719" | 17.066 mm |
| 11/16" | 0.6875" | 17.462 mm |
| 45/64" | 0.7031" | 17.859 mm |
| 23/32" | 0.7188" | 18.256 mm |
| 47/64" | 0.7344" | 18.653 mm |
| 3/4" | 0.7500" | 19.050 mm |
| 49/64" | 0.7656" | 19.447 mm |
| 25/32" | 0.7813" | 19.844 mm |
| 51/64" | 0.7969" | 20.241 mm |
| 13/16" | 0.8125" | 20.637 mm |
| 53/64" | 0.8281" | 21.034 mm |
| 27/32" | 0.8438" | 21.431 mm |
| 55/64" | 0.8594" | 21.828 mm |
| 7/8" | 0.8750" | 22.225 mm |
| 57/64" | 0.8906" | 22.622 mm |
| 29/32" | 0.9063" | 23.019 mm |
| 59/64" | 0.9219" | 23.416 mm |
| 15/16" | 0.9375" | 23.813 mm |
| 61/64" | 0.9531" | 24.209 mm |
| 31/32" | 0.9688" | 24.606 mm |
| 63/64" | 0.9844" | 25.003 mm |
| 1" | 1.0000" | 25.400 mm |
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Frequently Asked Questions
How many mm is 1/4 inch?
1/4 inch equals exactly 6.35 millimeters. This is one of the most common conversions in machining. Multiply any inch value by 25.4 to get millimeters. Other frequent conversions: 1/8" = 3.175 mm, 3/8" = 9.525 mm, 1/2" = 12.7 mm, and 1" = 25.4 mm exactly by international definition.
What is 0.375 inches as a fraction?
0.375 inches equals 3/8 inch. To convert a decimal to a fraction, multiply by the desired denominator (e.g., 0.375 x 8 = 3, giving 3/8). In machining, common denominators are 8ths, 16ths, 32nds, and 64ths. If the result is not a whole number, round to the nearest fraction and note the deviation.