Engineering Tools
Decimal & Metric Equivalents
Quick-reference conversion chart for fractions, decimals, and millimeters — bookmark it for the shop floor.
Fraction → Decimal → Millimeter
Highlighted rows indicate standard fractional inch values.
| Fractions | Decimals | mm |
|---|---|---|
| — | 0.00394 | 0.1 |
| — | 0.00787 | 0.2 |
| — | 0.01181 | 0.3 |
| 1/64 | 0.015625 | 0.3969 |
| — | 0.01575 | 0.4 |
| — | 0.01969 | 0.5 |
| — | 0.02362 | 0.6 |
| — | 0.02756 | 0.7 |
| 1/32 | 0.03125 | 0.7938 |
| — | 0.0315 | 0.8 |
| — | 0.03543 | 0.9 |
| — | 0.03937 | 1 |
| 3/64 | 0.046875 | 1.1906 |
| 1/16 | 0.0625 | 1.5875 |
| 5/64 | 0.078125 | 1.9844 |
| — | 0.07874 | 2 |
| 3/32 | 0.09375 | 2.3813 |
| 7/64 | 0.109375 | 2.7781 |
| — | 0.11811 | 3 |
| 1/8 | 0.125 | 3.175 |
| 9/64 | 0.140625 | 3.5719 |
| 5/32 | 0.15625 | 3.9688 |
| — | 0.15748 | 4 |
| 11/64 | 0.171875 | 4.3656 |
| 3/16 | 0.1875 | 4.7625 |
| — | 0.19685 | 5 |
| 13/64 | 0.203125 | 5.1594 |
| 7/32 | 0.21875 | 5.5563 |
| — | 0.23622 | 6 |
| 15/64 | 0.234375 | 5.9531 |
| 1/4 | 0.25 | 6.35 |
| — | 0.27559 | 7 |
| 17/64 | 0.265625 | 6.7469 |
| Fractions | Decimals | mm |
|---|---|---|
| 9/32 | 0.28125 | 7.1438 |
| 19/64 | 0.296875 | 7.5406 |
| 5/16 | 0.3125 | 7.9375 |
| 21/64 | 0.328125 | 8.3344 |
| 11/32 | 0.34375 | 8.7313 |
| — | 0.35433 | 9 |
| 23/64 | 0.359375 | 9.1281 |
| 3/8 | 0.375 | 9.525 |
| 25/64 | 0.390625 | 9.9219 |
| — | 0.3937 | 10 |
| 13/32 | 0.40625 | 10.3188 |
| 27/64 | 0.421875 | 10.7156 |
| — | 0.43307 | 11 |
| 7/16 | 0.4375 | 11.1125 |
| 29/64 | 0.453125 | 11.5094 |
| 15/32 | 0.46875 | 11.9063 |
| — | 0.47244 | 12 |
| 31/64 | 0.484375 | 12.3031 |
| 1/2 | 0.5 | 12.7 |
| — | 0.51181 | 13 |
| 33/64 | 0.515625 | 13.0969 |
| 17/32 | 0.53125 | 13.4938 |
| — | 0.53125 | 13.4938 |
| 35/64 | 0.546875 | 13.8907 |
| — | 0.55118 | 14 |
| 9/16 | 0.5625 | 14.2875 |
| 37/64 | 0.578125 | 14.6844 |
| — | 0.59055 | 15 |
| 19/32 | 0.59375 | 15.0813 |
| 39/64 | 0.609375 | 15.4781 |
| 5/8 | 0.625 | 15.875 |
| — | 0.62992 | 16 |
| 41/64 | 0.640625 | 16.2719 |
| Fractions | Decimals | mm |
|---|---|---|
| 21/32 | 0.65625 | 16.6688 |
| — | 0.66929 | 17 |
| 43/64 | 0.671875 | 17.0657 |
| 11/16 | 0.6875 | 17.4625 |
| 45/64 | 0.703125 | 17.8594 |
| — | 0.70866 | 18 |
| 23/32 | 0.71875 | 18.2563 |
| 47/64 | 0.734375 | 18.6532 |
| — | 0.74803 | 19 |
| 3/4 | 0.75 | 19.05 |
| 49/64 | 0.765625 | 19.4469 |
| 25/32 | 0.78125 | 19.8438 |
| — | 0.78740 | 20 |
| 51/64 | 0.796875 | 20.2407 |
| 13/16 | 0.8125 | 20.6375 |
| — | 0.82677 | 21 |
| 53/64 | 0.828125 | 21.0344 |
| 27/32 | 0.84375 | 21.4313 |
| 55/64 | 0.859375 | 21.8282 |
| — | 0.86614 | 22 |
| 7/8 | 0.875 | 22.225 |
| 57/64 | 0.890625 | 22.6219 |
| — | 0.90551 | 23 |
| 29/32 | 0.90625 | 23.0188 |
| 59/64 | 0.921875 | 23.4157 |
| 15/16 | 0.9375 | 23.8125 |
| — | 0.94488 | 24 |
| 61/64 | 0.953125 | 24.2094 |
| 31/32 | 0.96875 | 24.6063 |
| — | 0.98425 | 25 |
| 63/64 | 0.984375 | 25.0031 |
| 1 | 1.000 | 25.4 |
Values rounded to 4 decimal places. 1 inch = 25.4 mm exactly.
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