Tap and Drill Bit Size Chart
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The charts below show you what size drill bit to use with a tap.
Tap sizes are shown as hole size – threads per inch. Example 1/4-20 = 1/4″ hole, 20 threads per inch.
Imperial / SAE tap and drill bit size table
| Tap | Fractional Drill Bit | Number Drill Bit | Letter Drill Bit |
|---|---|---|---|
| 0-80 | 3/64 | – | – |
| 1-64 | – | 53 | – |
| 2-56 | – | 50 | – |
| 3-48 | – | 47 | – |
| 4-40 | 3/32 | 43 | – |
| 5-40 | – | 38 | – |
| 6-32 | 7/64 | 35 | – |
| 8-32 | – | 29 | – |
| 10-24 | 5/32 | 25 | – |
| 10-32 | 5/32 | 21 | – |
| 12-24 | 11/64 | 16 | – |
| 1/4-20 | 13/64 | 7 | – |
| 1/4-28 | 7/32 | 3 | – |
| 5/16-18 | 17/64 | – | F |
| 5/16-24 | – | – | I |
| 3/8-16 | 5/16 | – | – |
| 3/8-24 | 21/64 | – | Q |
| 7/16-14 | 23/64 | – | U |
| 7/16-20 | 25/64 | – | – |
| 1/2-13 | 27/64 | – | – |
| 1/2-20 | 29/64 | – | – |
| 9/16-12 | 31/64 | – | – |
| 9/16-18 | 33/64 | – | – |
| 5/8-11 | 17/32 | – | – |
| 5/8-18 | 37/64 | – | – |
| 3/4-10 | 21/32 | – | – |
| 3/4-16 | 11/16 | – | – |
| Drill sizes are for 75% depth of thread. | |||
Metric tap and drill bit size table
Tap sizes are shown as hole size – threads per mm (millimeter). Example 6mm-1.0 = 6mm hole, 1 threads per mm.
| Tap | Metric Drill | Imperial Drill |
|---|---|---|
| 3 mm x 0.6 | 2.5 mm | – |
| 4 mm x 0.7 | 3.4 mm | – |
| 5 mm x 0.8 | 4.3 mm | – |
| 6 mm x 1.0 | 5.2 mm | – |
| 7 mm x 1.0 | 6.1 mm | 15/64 |
| 8 mm x 1.25 | 6.9 mm | 17/64 |
| 8 mm x 1.0 | 7.1 mm | – |
| 10 mm x 1.5 | 8.7 mm | – |
| 10 mm x 1.25 | 8.9 mm | 11/32 |
| 10 mm x 1.0 | 9.1 mm | – |
| 12 mm x 1.75 | 10.5 mm | – |
| 12 mm x 1.5 | 10.7 mm | 27/64 |
| 14 mm x 2.0 | 12.2 mm | – |
| 14 mm x 1.5 | 12.7 mm | – |
| 16 mm x 2.0 | 14.2 mm | 35/64 |
| 16 mm x 1.5 | 14.7 mm | – |
| Drill sizes are for 75% depth of thread. | ||
