Fraction64ths of an inch
The drill-chart grid: sixty-four marks, each with its reduced name, exact decimal and exact millimetres. For drills near these sizes, see BenchReference.
The site chrome drops away — just the numbers.
| 64ths | Reduced | Decimal | mm |
|---|---|---|---|
| 1/64 | — | 0.015625 | 0.396875 |
| 2/64 | 1/32 | 0.03125 | 0.79375 |
| 3/64 | — | 0.046875 | 1.190625 |
| 4/64 | 1/16 | 0.0625 | 1.5875 |
| 5/64 | — | 0.078125 | 1.984375 |
| 6/64 | 3/32 | 0.09375 | 2.38125 |
| 7/64 | — | 0.109375 | 2.778125 |
| 8/64 | 1/8 | 0.125 | 3.175 |
| 9/64 | — | 0.140625 | 3.571875 |
| 10/64 | 5/32 | 0.15625 | 3.96875 |
| 11/64 | — | 0.171875 | 4.365625 |
| 12/64 | 3/16 | 0.1875 | 4.7625 |
| 13/64 | — | 0.203125 | 5.159375 |
| 14/64 | 7/32 | 0.21875 | 5.55625 |
| 15/64 | — | 0.234375 | 5.953125 |
| 16/64 | 1/4 | 0.25 | 6.35 |
| 17/64 | — | 0.265625 | 6.746875 |
| 18/64 | 9/32 | 0.28125 | 7.14375 |
| 19/64 | — | 0.296875 | 7.540625 |
| 20/64 | 5/16 | 0.3125 | 7.9375 |
| 21/64 | — | 0.328125 | 8.334375 |
| 22/64 | 11/32 | 0.34375 | 8.73125 |
| 23/64 | — | 0.359375 | 9.128125 |
| 24/64 | 3/8 | 0.375 | 9.525 |
| 25/64 | — | 0.390625 | 9.921875 |
| 26/64 | 13/32 | 0.40625 | 10.31875 |
| 27/64 | — | 0.421875 | 10.715625 |
| 28/64 | 7/16 | 0.4375 | 11.1125 |
| 29/64 | — | 0.453125 | 11.509375 |
| 30/64 | 15/32 | 0.46875 | 11.90625 |
| 31/64 | — | 0.484375 | 12.303125 |
| 32/64 | 1/2 | 0.5 | 12.7 |
| 64ths | Reduced | Decimal | mm |
|---|---|---|---|
| 33/64 | — | 0.515625 | 13.096875 |
| 34/64 | 17/32 | 0.53125 | 13.49375 |
| 35/64 | — | 0.546875 | 13.890625 |
| 36/64 | 9/16 | 0.5625 | 14.2875 |
| 37/64 | — | 0.578125 | 14.684375 |
| 38/64 | 19/32 | 0.59375 | 15.08125 |
| 39/64 | — | 0.609375 | 15.478125 |
| 40/64 | 5/8 | 0.625 | 15.875 |
| 41/64 | — | 0.640625 | 16.271875 |
| 42/64 | 21/32 | 0.65625 | 16.66875 |
| 43/64 | — | 0.671875 | 17.065625 |
| 44/64 | 11/16 | 0.6875 | 17.4625 |
| 45/64 | — | 0.703125 | 17.859375 |
| 46/64 | 23/32 | 0.71875 | 18.25625 |
| 47/64 | — | 0.734375 | 18.653125 |
| 48/64 | 3/4 | 0.75 | 19.05 |
| 49/64 | — | 0.765625 | 19.446875 |
| 50/64 | 25/32 | 0.78125 | 19.84375 |
| 51/64 | — | 0.796875 | 20.240625 |
| 52/64 | 13/16 | 0.8125 | 20.6375 |
| 53/64 | — | 0.828125 | 21.034375 |
| 54/64 | 27/32 | 0.84375 | 21.43125 |
| 55/64 | — | 0.859375 | 21.828125 |
| 56/64 | 7/8 | 0.875 | 22.225 |
| 57/64 | — | 0.890625 | 22.621875 |
| 58/64 | 29/32 | 0.90625 | 23.01875 |
| 59/64 | — | 0.921875 | 23.415625 |
| 60/64 | 15/16 | 0.9375 | 23.8125 |
| 61/64 | — | 0.953125 | 24.209375 |
| 62/64 | 31/32 | 0.96875 | 24.60625 |
| 63/64 | — | 0.984375 | 25.003125 |
| 64/64 | 1 | 1 | 25.4 |
Neighbouring rules: 16ths · 32nds · 128ths
Common questions
- Why are drill sizes given in 64ths?
- Fractional drill sets step by 64ths because that is the finest rule fractional tooling is made to. Between those steps live the number and letter gauge drills — a different system, listed on BenchReference.
- How big is 1/64 of an inch in millimetres?
- 1/64″ is exactly 0.396875 mm — about the thickness of four sheets of paper. Every mm value here is exact.