Drill bit Length Chart
The table shows the sizes of straight shank drills.
In the United States, three different systems for designating twist drill sizes are used:
- letters (Morse gauge)
- fractional inches
- millimeters
- numbers, with higher numbers representing smaller drills.
The lengths in the table are “jobber’s lengths”. Very long twist drills, (“aircraft drills” or “electrician’s drill”) are available in 6, 12, and even 24-inch lengths.
| Size | Long Length | Regular Length | Short Length | ||||
| Size | Flute Length | Flute Length | Overall Length | Overall Length | Dec. | Flute Length | Overall Length |
| 1/64 | 5/16 | 3/16 | 3/4 | 1-1/2 | 0.0156 | ||
| 1/32 | 3/4 | 1/2 | 1-3/8 | 2 | 0.0312 | ||
| 3/64 | 1-1/8 | 3/4 | 1-3/4 | 2-1/4 | 0.0469 | 1/2 | 1-3/8 |
| 1/16 | 1-3/4 | 7/8 | 1-7/8 | 3 | 0.0625 | 5/8 | 1-5/8 |
| 5/64 | 2 | 1 | 2 | 3-3/4 | 0.0781 | 11/16 | 1-11/16 |
| 3/32 | 2-1/4 | 1-1/4 | 2-1/4 | 4-1/4 | 0.0937 | 3/4 | 1-3/4 |
| 7/64 | 2-1/2 | 1-1/2 | 2-5/8 | 4-5/8 | 0.1094 | 13/16 | 1-13/16 |
| 1/8 | 2-3/4 | 1-5/8 | 2-3/4 | 5-1/8 | 0.1250 | 7/8 | 1-7/8 |
| 9/64 | 3 | 1-3/4 | 2-7/8 | 5-3/8 | 0.1406 | 15/16 | 1-15/16 |
| 5/32 | 3 | 2 | 3-1/8 | 5-3/8 | 0.1562 | 1 | 2-1/16 |
| 11/64 | 3-3/8 | 2-1/8 | 3-1/4 | 5-3/4 | 0.1719 | 1-1/16 | 2-1/8 |
| 3/16 | 3-3/8 | 2-5/16 | 3-1/2 | 5-3/4 | 0.1875 | 1-1/8 | 2-3/16 |
| 13/64 | 3-5/8 | 2-7/16 | 3-5/8 | 6 | 0.2031 | 1-3/16 | 2-1/4 |
| 7/32 | 3-5/8 | 2-1/2 | 3-3/4 | 6 | 0.2188 | 1-1/4 | 2-3/8 |
| 15/64 | 3-3/4 | 2-5/8 | 3-7/8 | 6-1/8 | 0.2344 | 1-5/16 | 2-7/16 |
| 1/4 | 3-3/4 | 2-3/4 | 4 | 6-1/8 | 0.2500 | 1-3/8 | 2-1/2 |
| 17/64 | 3-7/8 | 2-7/8 | 4-1/8 | 6-1/4 | 0.2656 | 1-7/16 | 2-5/8 |
| 9/32 | 3-7/8 | 2-15/16 | 4-1/4 | 6-1/4 | 0.2812 | 1-1/2 | 2-11/16 |
| 19/64 | 4 | 3-1/16 | 4-3/8 | 6-3/8 | 0.2969 | 1-9/16 | 2-3/4 |
| 5/16 | 4 | 3-3/16 | 4-1/2 | 6-3/8 | 0.3125 | 1-5/8 | 2-13/16 |
| 21/64 | 4-1/8 | 3-5/16 | 4-5/8 | 6-1/2 | 0.3281 | 1-11/16 | 2-15/16 |
| 11/32 | 4-1/8 | 3-7/16 | 4-3/4 | 6-1/2 | 0.3438 | 1-11/16 | 3 |
| 23/64 | 4-1/4 | 3-1/2 | 4-7/8 | 6-3/4 | 0.3594 | 1-3/4 | 3-1/16 |
| 3/8 | 4-1/4 | 3-5/8 | 5 | 6-3/4 | 0.3750 | 1-13/16 | 3-1/8 |
| 25/64 | 4-3/8 | 3-3/4 | 5-1/8 | 7 | 0.3906 | 1-7/8 | 3-1/4 |
| 13/32 | 4-3/8 | 3-7/8 | 5-1/4 | 7 | 0.4062 | 1-15/16 | 3-5/16 |
| 27/64 | 4-5/8 | 3-15/16 | 5-3/8 | 7-1/4 | 0.4219 | 2 | 3-3/8 |
| 7/16 | 4-5/8 | 4-1/16 | 5-1/2 | 7-1/4 | 0.4375 | 2-1/16 | 3-7/16 |
| 29/64 | 4-3/4 | 4-3/16 | 5-5/8 | 7-1/2 | 0.4531 | 2-1/8 | 3-9/16 |
| 15/32 | 4-3/4 | 4-5/16 | 5-3/4 | 7-1/2 | 0.4688 | 2-1/8 | 3-5/8 |
| 31/64 | 4-3/4 | 4-3/8 | 5-7/8 | 7-3/4 | 0.4844 | 2-3/16 | 3-11/16 |
| 1/2 | 4-3/4 | 4-1/2 | 6 | 7-3/4 | 0.5000 | 2-1/4 | 3-3/4 |
| 33/64 | 4-3/4 | 4-13/16 | 6-5/8 | 8 | 0.5156 | 2-3/8 | 3-7/8 |
| 17/32 | 4-3/4 | 4-13/16 | 6-5/8 | 8 | 0.5312 | 2-3/8 | 3-7/8 |
| 35/64 | 4-7/8 | 4-1316 | 6-5/8 | 8-1/4 | 0.5469 | 2-1/2 | 4 |
| 9/16 | 4-7/8 | 4-13/16 | 6-5/8 | 8-1/4 | 0.5625 | 2-1/2 | 4 |
| 37/64 | 4-7/8 | 4-13/16 | 6-5/8 | 8-3/4 | 0.5781 | 2-5/8 | 4-1/8 |
| 19/32 | 4-7/8 | 5-3/16 | 7-1/8 | 8-3/4 | 0.5938 | 2-5/8 | 4-1/8 |
| 39/64 | 4-7/8 | 5-3/16 | 7-1/8 | 8-3/4 | 0.6094 | 2-3/4 | 4-1/4 |
| 5/8 | 4-7/8 | 5-3/16 | 7-1/8 | 8-3/4 | 0.6250 | 2-3/4 | 4-1/4 |
| 41/64 | 5-1/8 | 5-3/16 | 7-1/8 | 9 | 0.6406 | 2-7/8 | 4-1/2 |
| 21/32 | 5-1/8 | 5-3/16 | 7-1/8 | 9 | 0.6562 | 2-7/8 | 4-1/2 |
| 43/64 | 5-3/8 | 5-5/8 | 7-5/8 | 9-1/4 | 0.6719 | 2-7/8 | 4-5/8 |
| 11/16 | 5-3/8 | 5-5/8 | 7-5/8 | 9-1/4 | 0.6875 | 2-7/8 | 4-5/8 |
| 45/64 | 5-5/8 | 9-1/2 | 0.7031 | 3 | 4-3/4 | ||
| 23/32 | 5-5/8 | 9-1/2 | 0.7188 | 3 | 4-3/4 | ||
| 47/64 | 5-7/8 | 9-3/4 | 0.7344 | 3-1/8 | 5 | ||
| 3/4 | 5-7/8 | 9-3/4 | 0.7500 | 3-1/8 | 5 | ||
| 49/64 | 6 | 9-7/8 | 0.7656 | 3-1/4 | 5-1/8 | ||
| 25/32 | 6 | 9-7/8 | 0.7812 | 3-1/4 | 5-1/8 | ||
| 51/64 | 6-1/8 | 10 | 0.7969 | 3-3/8 | 5-1/4 | ||
| 13/16 | 6-1/8 | 10 | 0.8125 | 3-3/8 | 5-1/4 | ||
| 53/64 | 6-1/8 | 10 | 0.8281 | 3-1/2 | 5-3/8 | ||
| 27/32 | 6-1/8 | 10 | 0.8438 | 3-1/2 | 5-3/8 | ||
| 55/64 | 6-1/8 | 10 | 0.8594 | 3-1/2 | 5-1/2 | ||
| 7/8 | 6-1/8 | 10 | 0.8750 | 3-1/2 | 5-1/2 | ||
| 57/64 | 6-1/8 | 10 | 0.8906 | 3-5/8 | 5-5/8 | ||
| 29/32 | 6-1/8 | 10 | 0.9062 | 3-5/8 | 5-5/8 | ||
| 59/64 | 6-1/8 | 10-3/4 | 0.9219 | 3-3/4 | 5-3/4 | ||
| 15/16 | 6-1/8 | 10-3/4 | 0.9375 | 3-3/4 | 5-3/4 | ||
| 61/64 | 6-3/8 | 11 | 0.9531 | 3-7/8 | 5-7/8 | ||
| 31/32 | 6-3/8 | 11 | 0.9688 | 3-7/8 | 5-7/8 | ||
| 63/64 | 6-3/8 | 11 | 0.9844 | 4 | 6 | ||
| 1 | 6-3/8 | 11 | 10.000 | 4 | 6 | ||
| 1-1/8 | 7-1/8 | 11-3/4 | 10.125 | 4 | 6-3/8 | ||
