| Major diameter (in mm) | Threads per inch (Pitch) | Tap drill size – Preferred sizes | ||||
| Coarse (UNC) | Fine (UNF) | Extra fine (UNEF) | Coarse | Fine | Extra fine | |
| #0 = 0.0600 (1.5240) | – | 80 | 3/64 in | |||
| #1 = 0.0730 (1.8542) | 64 | 72 | #53 | #53 | ||
| #2 = 0.0860 (2.1844) | 56 | 64 | #50 | #50 | ||
| #3 = 0.0990 (2.5146) | 48 | 56 | #47 | #45 | ||
| #4 = 0.1120 (2.8448) | 40 | 48 | #43 | #42 | ||
| #5 = 0.1250 (3.1750) | 40 | 44 | #38 | #37 | ||
| #6 = 0.1380 (3.5052) | 32 | 40 | #36 | #33 | ||
| #8 = 0.1640 (4.1656) | 32 | 36 | #29 | #29 | ||
| #10 = 0.1900 (4.8260) | 24 | 32 | #25 | #21 | ||
| #12 = 0.2160 (5.4864) | 24 | 28 | 32 | #16 | #14 | |
| 1/4 = 0.2500 (6.3500) | 20 | 28 | 32 | #7 | #3 | |
| 5/16 = 0.3125 (7.9375) | 18 | 24 | 32 | F | I | |
| 3/8 = 0.3750 (9.5250) | 16 | 24 | 32 | 5/16 in | Q | |
| 7/16 = 0.4375 (11.1125) | 14 | 20 | 28 | U | 25/64 in | |
| 1/2 = 0.5000 (12.7000) | 13 | 20 | 28 | 27/64 in | 29/64 in | |
| 9/16 = 0.5625 (14.2875) | 12 | 18 | 24 | 31/64 in | 33/64 in | |
| 5/8 = 0.6250 (15.8750) | 11 | 18 | 24 | 17/32 in | 37/64 in | |
| 3/4 = 0.7500 (19.0500) | 10 | 16 | 20 | 21/32 in | 11/16 in | |
| 7/8 = 0.8750 (22.2250) | 9 | 14 | 20 | 49/64 in | 13/16 in | |
- ASME/ANSI B1.1 – 2003 Unified Inch Screw Threads, UN & UNR Thread Form
- ASME/ANSI B1.10M – 2004 Unified Miniature Screw Threads
- ASME/ANSI B1.15 – 1995 Unified Inch Screw Threads, UNJ Thread Form
