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UNC Spec Table
UNC KS Specifications — 16 sizes
ASME B1.1
ANSIUNC
16 sizes| Nominal | TPI | Major Dia (mm) | Minor Dia (mm) | Stress Area Aₛ (mm²) | Standard |
|---|---|---|---|---|---|
| #4-40 | 40 | 2.845 | 2.065 | 3.9 | ASME B1.1 |
| #6-32 | 32 | 3.505 | 2.532 | 5.86 | ASME B1.1 |
| #8-32 | 32 | 4.166 | 3.193 | 9.03 | ASME B1.1 |
| #10-24 | 24 | 4.826 | 3.528 | 11.29 | ASME B1.1 |
| 1/4-20 | 20 | 6.35 | 4.793 | 20.52 | ASME B1.1 |
| 5/16-18 | 18 | 7.938 | 6.205 | 33.81 | ASME B1.1 |
| 3/8-16 | 16 | 9.525 | 7.577 | 50 | ASME B1.1 |
| 7/16-14 | 14 | 11.112 | 8.887 | 68.58 | ASME B1.1 |
| 1/2-13 | 13 | 12.7 | 10.302 | 91.55 | ASME B1.1 |
| 9/16-12 | 12 | 14.287 | 11.692 | 117.42 | ASME B1.1 |
| 5/8-11 | 11 | 15.875 | 13.043 | 145.81 | ASME B1.1 |
| 3/4-10 | 10 | 19.05 | 15.933 | 215.48 | ASME B1.1 |
| 7/8-9 | 9 | 22.225 | 18.763 | 298.06 | ASME B1.1 |
| 1-8 | 8 | 25.4 | 21.504 | 390.97 | ASME B1.1 |
| 1 1/4-7 | 7 | 31.75 | 27.297 | 625.16 | ASME B1.1 |
| 1 1/2-6 | 6 | 38.1 | 32.906 | 906.45 | ASME B1.1 |
This specification follows ANSI/ASME (American National Standards). Inch-based units apply; required for maintaining US/Canadian equipment and meeting North American market requirements.
UNC (Unified National Coarse) is the standard coarse-pitch inch thread per ASME B1.1. This table covers #4 through 1½ inch with major diameter, TPI (threads per inch), minor diameter, and stress area. Commonly found on imported North-American equipment, aerospace, automotive, and heavy machinery as the default coarse inch fastener interface — its larger pitch (vs. UNF) suits softer metals and high-volume assembly lines.