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Bolt Thread Dimensions: UNF
0.25 to 1
Bolt thread dimensions — UNC, UNF, ISO coarse/fine thread series with pitch, tensile stress area, and threads per inch
| thread series | nominal diameter | gross area in2 (in2) | minor diameter in (in) | nominal size | pitch mm (mm) | root area in2 (in2) | tensile stress area in2 (in2) | tensile stress area mm2 (mm2) | threads per inch (threads/in) |
|---|---|---|---|---|---|---|---|---|---|
| UNF | 0.25 | 0.0491 | 0.2113 | 1/4 | 0.9071 | 0.0291 | 0.0364 | 23.48 | 28 |
| UNF | 0.3125 | 0.0767 | 0.2674 | 5/16 | 1.0583 | 0.0464 | 0.058 | 37.42 | 24 |
| UNF | 0.375 | 0.1104 | 0.3299 | 3/8 | 1.0583 | 0.0702 | 0.0878 | 56.65 | 24 |
| UNF | 0.4375 | 0.1503 | 0.3834 | 7/16 | 1.27 | 0.095 | 0.1187 | 76.58 | 20 |
| UNF | 0.5 | 0.1963 | 0.4459 | 1/2 | 1.27 | 0.1279 | 0.1599 | 103.16 | 20 |
| UNF | 0.5625 | 0.2485 | 0.5024 | 9/16 | 1.4111 | 0.1624 | 0.203 | 130.97 | 18 |
| UNF | 0.625 | 0.3068 | 0.5649 | 5/8 | 1.4111 | 0.2048 | 0.256 | 165.16 | 18 |
| UNF | 0.75 | 0.4418 | 0.6823 | 3/4 | 1.5875 | 0.2984 | 0.373 | 240.64 | 16 |
| UNF | 0.875 | 0.6013 | 0.7977 | 7/8 | 1.8143 | 0.4076 | 0.5095 | 328.71 | 14 |
| UNF | 1 | 0.7854 | 0.9098 | 1 | 2.1167 | 0.5304 | 0.663 | 427.74 | 12 |
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