This launch reference focuses on common shop sizes and links each tap drill recommendation to the data source. It does not reproduce ASME dimensional tolerance tables.
UNC and UNF diameter and pitch chart
Rows show the nominal major diameter, series, TPI and the stored cutting-tap drill recommendation.
| Designation | Series | Nominal diameter | TPI | Tap drill |
|---|---|---|---|---|
| #4-40 | UNC | 0.1120 in | 40 | #43 · 0.0890 in |
| #6-32 | UNC | 0.1380 in | 32 | #36 · 0.1065 in |
| #8-32 | UNC | 0.1640 in | 32 | #29 · 0.1360 in |
| #10-24 | UNC | 0.1900 in | 24 | #26 · 0.1470 in |
| #10-32 | UNF | 0.1900 in | 32 | #21 · 0.1590 in |
| 1/4-20 | UNC | 0.2500 in | 20 | #7 · 0.2010 in |
| 1/4-28 | UNF | 0.2500 in | 28 | #3 · 0.2130 in |
| 5/16-18 | UNC | 0.3125 in | 18 | F · 0.2570 in |
| 3/8-16 | UNC | 0.3750 in | 16 | 5/16 in · 0.3125 in |
| 3/8-24 | UNF | 0.3750 in | 24 | Q · 0.3320 in |
| 1/2-13 | UNC | 0.5000 in | 13 | 27/64 in · 0.421875 in |
| #4-48 | UNF | 0.1120 in | 48 | #42 · 0.0935 in |
| #6-40 | UNF | 0.1380 in | 40 | #33 · 0.1130 in |
| #8-36 | UNF | 0.1640 in | 36 | #29 · 0.1360 in |
| #12-24 | UNC | 0.2160 in | 24 | #16 · 0.1770 in |
| #12-28 | UNF | 0.2160 in | 28 | #15 · 0.1800 in |
| 5/16-24 | UNF | 0.3125 in | 24 | I · 0.2720 in |
| 7/16-14 | UNC | 0.4375 in | 14 | U · 0.3680 in |
| 7/16-20 | UNF | 0.4375 in | 20 | 25/64 in · 0.390625 in |
| 1/2-20 | UNF | 0.5000 in | 20 | 29/64 in · 0.453125 in |
| 9/16-12 | UNC | 0.5625 in | 12 | 31/64 in · 0.484375 in |
| 9/16-18 | UNF | 0.5625 in | 18 | 33/64 in · 0.515625 in |
| 5/8-11 | UNC | 0.6250 in | 11 | 17/32 in · 0.53125 in |
| 5/8-18 | UNF | 0.6250 in | 18 | 37/64 in · 0.578125 in |
| 3/4-10 | UNC | 0.7500 in | 10 | 21/32 in · 0.65625 in |
| 3/4-16 | UNF | 0.7500 in | 16 | 11/16 in · 0.6875 in |
| 7/8-9 | UNC | 0.8750 in | 9 | 49/64 in · 0.765625 in |
| 7/8-14 | UNF | 0.8750 in | 14 | 13/16 in · 0.8125 in |
| 1-8 | UNC | 1.0000 in | 8 | 7/8 in · 0.8750 in |
| 1-12 | UNF | 1.0000 in | 12 | 59/64 in · 0.921875 in |
Coarse versus fine
For a given nominal diameter, UNF has more threads per inch and therefore a smaller pitch. That changes tap drill selection, thread depth, adjustment sensitivity and behavior in a joint.
- Write the diameter and TPI together.
- Use the series when documentation requires it.
- Do not infer strength or suitability from coarse/fine alone.
Thread classes
Unified thread class adds fit and tolerance information. A tap-drill lookup by itself does not define the finished internal thread class; tooling, process and gauging do.
Important limitation
For a design decision, consult the licensed current standard and application requirements. This page is a navigation and workshop reference.
For a design decision, consult the licensed current standard and application requirements. This page is a navigation and workshop reference.
Technical references
- ASME B1.1-2024 Unified Inch Screw Threads — ASME. Accessed 2026-11-10.
- Cle-Line C01112 Tap and Drill Recommendations — Greenfield Industries / Cle-Line. Accessed 2026-11-09.
Standards references identify scope and terminology; protected dimensional tables are not reproduced.