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UNF Spec Table
UNF KS Specifications — 11 sizes
ASME B1.1
ANSIUNF
11 sizes| Nominal | TPI | Major Dia (mm) | Minor Dia (mm) | Stress Area Aₛ (mm²) | Standard |
|---|---|---|---|---|---|
| #4-48 | 48 | 2.845 | 2.195 | 4.26 | ASME B1.1 |
| #6-40 | 40 | 3.505 | 2.725 | 6.55 | ASME B1.1 |
| #8-36 | 36 | 4.166 | 3.299 | 9.51 | ASME B1.1 |
| #10-32 | 32 | 4.826 | 3.853 | 12.9 | ASME B1.1 |
| 1/4-28 | 28 | 6.35 | 5.237 | 23.48 | ASME B1.1 |
| 5/16-24 | 24 | 7.938 | 6.64 | 37.42 | ASME B1.1 |
| 3/8-24 | 24 | 9.525 | 8.227 | 56.65 | ASME B1.1 |
| 1/2-20 | 20 | 12.7 | 11.143 | 103.16 | ASME B1.1 |
| 5/8-18 | 18 | 15.875 | 14.143 | 165.16 | ASME B1.1 |
| 3/4-16 | 16 | 19.05 | 17.102 | 240.64 | ASME B1.1 |
| 1-12 | 12 | 25.4 | 22.804 | 427.74 | 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.
UNF (Unified National Fine) is the fine-pitch inch thread per ASME B1.1 — more threads per inch (TPI) than UNC at the same major diameter, giving a smaller pitch. Used in vibration-prone environments, thin-walled parts, and precision machinery. This table lists #4 through 1 inch with major dia, TPI, minor dia, and stress area. Common in aerospace structures, instrumentation, and adjustment screws.