Thread Size Chart（UNC&UNF）
The table below provides a quick reference chart for UNC/UNF (Unified National Threads). It details the types, sizes, and specifications of Unified Coarse Thread (UNC) and Unified Fine Thread (UNF). This facilitates understanding the dimensional specifications of these threads.
Thread sizes are not directly interchangeable. For guidance onlyUNC Thread Table
| Thread | Thread Per Inch | Major Diameter | Minor Diameter Male Thread | Pitch | Tap Drill |
| #1-64 | 64 | 0.0730 | 0.0561 | 0.397 | 4.50 |
| #2-56 | 56 | 0.0860 | 0.0667 | 0.453 | 1.80 |
| #3-48 | 48 | 0.0990 | 0.0764 | 0.529 | 2.10 |
| #4- 40 | 40 | 0.1120 | 0.0849 | 0.635 | 2.35 |
| #5-40 | 40 | 0.1250 | 0.0979 | 0.635 | 2.65 |
| #6- 32 | 32 | 0.1380 | 0.1042 | 0.794 | 2.85 |
| #8- 32 | 32 | 0.1640 | 0.1302 | 0.794 | 3.50 |
| #10-24 | 24 | 0.1900 | 0.1449 | 1.058 | 4.00 |
| #12-24 | 24 | 0.2160 | 0.1709 | 1.058 | 4.65 |
| 1/4- 20 | 20 | 0.2500 | 0.1959 | 1.270 | 5.35 |
| 5/16-18 | 18 | 0.3125 | 0.2524 | 1.411 | 6.80 |
| 3/8- 16 | 16 | 0.3750 | 0.3073 | 1.587 | 8.25 |
| 7/16-14 | 14 | 0.4375 | 0.3602 | 1.814 | 9.65 |
| 1/2-13 | 13 | 0.5000 | 0.4167 | 1.954 | 11.15 |
| 9/16-12 | 12 | 0.5625 | 0.4723 | 2.117 | 12.60 |
| 5/8-11 | 11 | 0.6250 | 0.5266 | 2.309 | 14.05 |
| 3/4 -10 | 10 | 0.7500 | 0.6417 | 2.540 | 17.00 |
| 7/8-8 | 8 | 0.8750 | 0.7547 | 2.822 | 20.00 |
| 1-8 | 8 | 1.000 | 0.8647 | 3.175 | 22.85 |
UNF Thread Table
| Thread | Thread Per Inch | Major Diameter | Minor Diameter Male Thread | Pitch | Tap Drill |
| #0-80 | 80 | 0.0600 | 0.0451 | 0.317 | 1.25 |
| #1-72 | 72 | 0.0730 | 0.0565 | 0.353 | 1.55 |
| #2-64 | 64 | 0.0860 | 0.0674 | 0.397 | 1.90 |
| #3- 56 | 56 | 0.0990 | 0.0778 | 0.453 | 2.15 |
| #4-48 | 48 | 0.1120 | 0.0871 | 0.529 | 2.40 |
| #5-44 | 44 | 0.1250 | 0.0979 | 0.577 | 2.70 |
| #6- 40 | 40 | 0.1380 | 0.1082 | 0.635 | 2.95 |
| #8-36 | 36 | 0.1640 | 0.1309 | 0.635 | 2.95 |
| #10-32 | 32 | 0.1900 | 0.1528 | 0.794 | 4.10 |
| #12-28 | 28 | 0.2160 | 0.1734 | 0.907 | 4.70 |
| 1/4” – 28 | 28 | 0.2500 | 0.2074 | 0.907 | 5.50 |
| 5/16”- 24 | 24 | 0.3125 | 0.2629 | 1.058 | 6.90 |
| 3/8″- 24 | 24 | 0.3750 | 0.3254 | 1.058 | 8.50 |
| 7/16″- 20 | 20 | 0.4375 | 0.3780 | 1.270 | 9.90 |
| 1/2″- 20 | 20 | 0.5000 | 0.4405 | 1.270 | 11.50 |
| 9/16″-18 | 18 | 0.5625 | 0.4964 | 1.441 | 12.90 |
| 5/8”-18 | 18 | 0.6250 | 0.5589 | 1.411 | 14.50 |
| 3/4”-16 | 16 | 0.7500 | 0.6763 | 1.587 | 17.50 |
| 7/8″-14 | 14 | 0.8750 | 0.7900 | 1.814 | 20.40 |
UNC Threads
UNC threads are unified coarse pitch threads.
- Less likely to cross-thread
- Faster assembly and disassembly (Generally used in mass production)
- Large thread allowances allow for thicker platings & coatings
- Fewer threads per distance compared to fine threads
UNF Threads
UNF threads are unified fine pitch threads.
- Allow for closer adjustment accuracy due to the smaller helix angle
- Require less torque to develop equivalent bolt preloads
- Fine thread is stronger in both tension (due to larger stress area) and shear (larger minor diameter)
- Less tendency to loosen since the thread incline is smaller
- Generally used for applications that need high fastener strength
UNF threads are unified fine pitch threads.
- Allow for closer adjustment accuracy due to the smaller helix angle
- Require less torque to develop equivalent bolt preloads
- Fine thread is stronger in both tension (due to larger stress area) and shear (larger minor diameter)
- Less tendency to loosen since the thread incline is smaller
- Generally used for applications that need high fastener strength
