This reference provides conversion formulas and a complete equivalents table for fractional inches, decimal inches and millimeters. The table covers all 64th-inch increments from 1/64 inch through 1 inch with their exact decimal and metric equivalents. Machinists and engineers use these conversions to translate between imperial and metric measurement systems.
How do you convert metric size to decimal equivalent?
Multiply the metric size (in millimeters) by 0.03937 to obtain the decimal equivalent in inches.
Formula: METRIC SIZE × 0.03937 = DECIMAL EQUIVALENT
How do you convert decimal size to metric equivalent?
Multiply the decimal size (in inches) by 25.4 to obtain the metric equivalent in millimeters.
Formula: DECIMAL SIZE × 25.4 = METRIC EQUIVALENT
Fractional, decimal and metric equivalents table
This table lists all 64th-inch fractional sizes from 1/64 inch to 1 inch with their decimal inch and millimeter equivalents.
| Fraction Of Inch | Decimal Of Inch | Millimeters | Fraction Of Inch | Decimal of Inch | Millimeters |
|---|---|---|---|---|---|
| 1/64 | .015625 | 0.3969 | 33/64 | .515625 | 13.0969 |
| 1/32 | .03125 | 0.7938 | 17/32 | .53125 | 13.4938 |
| 3/64 | .046875 | 1.1906 | 35/64 | .546875 | 13.8906 |
| 1/16 | .0625 | 1.5875 | 9/16 | .5625 | 14.2875 |
| 5/64 | .078125 | 1.9844 | 37/64 | .578125 | 14.6844 |
| 3/32 | .09375 | 2.3812 | 19/32 | .59375 | 15.0812 |
| 7/64 | .109375 | 2.7781 | 39/64 | .609375 | 15.4781 |
| 1/8 | .125 | 3.1750 | 5/8 | .625 | 15.8750 |
| 9/64 | .140625 | 3.5719 | 41/64 | .640625 | 16.2719 |
| 5/32 | .15625 | 3.9688 | 21/32 | .65625 | 16.6688 |
| 11/64 | .171875 | 4.3656 | 43/64 | .671875 | 17.0656 |
| 3/16 | .1875 | 4.7625 | 11/16 | .6875 | 17.4625 |
| 13/64 | .203125 | 5.1594 | 45/64 | .703125 | 17.8594 |
| 7/32 | .21875 | 5.5562 | 23/32 | .71875 | 18.2562 |
| 15/64 | .234375 | 5.9531 | 47/64 | .734375 | 18.6531 |
| 1/4 | .250 | 6.3500 | 3/4 | .750 | 19.0500 |
| 17/64 | .265625 | 6.7469 | 49/64 | .765625 | 19.4469 |
| 9/32 | .28125 | 7.1438 | 25/32 | .78125 | 19.8438 |
| 19/64 | .296875 | 7.5406 | 51/64 | .796875 | 20.2406 |
| 5/16 | .3125 | 7.9375 | 13/16 | .8125 | 20.6375 |
| 21/64 | .328125 | 8.3344 | 53/64 | .828125 | 21.0344 |
| 11/32 | .34375 | 8.7312 | 27/32 | .843750 | 21.4312 |
| 23/64 | .359375 | 9.1281 | 55/64 | .859375 | 21.8281 |
| 3/8 | .375 | 9.5250 | 7/8 | .875 | 22.2250 |
| 25/64 | .390625 | 9.9219 | 57/64 | .890625 | 22.6219 |
| 13/32 | .40625 | 10.3188 | 29/32 | .90625 | 23.0188 |
| 27/64 | .421875 | 10.7156 | 59/64 | .921875 | 23.4156 |
| 7/16 | .4375 | 11.1125 | 15/16 | .9375 | 23.8125 |
| 29/64 | .453125 | 11.5094 | 61/64 | .953125 | 24.2094 |
| 15/32 | .46875 | 11.9062 | 31/32 | .96875 | 24.6062 |
| 31/64 | .484375 | 12.3031 | 63/64 | .984375 | 25.0031 |
| 1/2 | .500 | 12.7000 | 1.000 | 1.0000 | 25.4000 |
Source and updates
Source: taylortool.com engineering data. Reviewed September 2026.