ASME B 18.2.1 Hex Cap Screws (2010); is the governing dimensional standard for inch-series hex bolts used in industrial, mechanical, and structural applications throughout North America and worldwide markets that use imperial measurements.
Dimensions of ASME B18.2.1 Hex Cap Screws (2010)
| Thread Size (d) | 1/4 | 5/16 | 3/8 | 7/16 | 1/2 | 9/16 | 5/8 | 3/4 | 7/8 | 1 | 1-1/8 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ds | max | 0.250 | 0.3125 | 0.375 | 0.4375 | 0.500 | 0.5625 | 0.625 | 0.750 | 0.875 | 1.000 | 1.125 |
| min | 0.245 | 0.3065 | 0.369 | 0.4305 | 0.493 | 0.5545 | 0.617 | 0.741 | 0.866 | 0.990 | 1.114 | |
| s | Basic | 7/16 | 1/2 | 9/16 | 5/8 | 3/4 | 13/16 | 15/16 | 1-1/8 | 1-5/16 | 1-1/2 | 1-11/16 |
| max | 0.438 | 0.500 | 0.562 | 0.625 | 0.750 | 0.812 | 0.938 | 1.125 | 1.312 | 1.500 | 1.688 | |
| min | 0.428 | 0.489 | 0.551 | 0.612 | 0.736 | 0.798 | 0.922 | 1.100 | 1.285 | 1.469 | 1.631 | |
| e | max | 0.505 | 0.577 | 0.650 | 0.722 | 0.866 | 0.938 | 1.083 | 1.299 | 1.516 | 1.732 | 1.949 |
| min | 0.488 | 0.557 | 0.628 | 0.698 | 0.840 | 0.910 | 1.051 | 1.254 | 1.465 | 1.675 | 1.859 | |
| k | Basic | 5/32 | 13/64 | 15/64 | 9/32 | 5/16 | 23/64 | 25/64 | 15/32 | 35/64 | 39/64 | 11/16 |
| max | 0.163 | 0.211 | 0.243 | 0.291 | 0.323 | 0.371 | 0.403 | 0.483 | 0.563 | 0.627 | 0.718 | |
| min | 0.150 | 0.195 | 0.226 | 0.272 | 0.302 | 0.348 | 0.378 | 0.455 | 0.531 | 0.591 | 0.658 | |
| kw | min | 0.106 | 0.140 | 0.160 | 0.195 | 0.215 | 0.250 | 0.269 | 0.324 | 0.378 | 0.416 | 0.461 |
| b | L≤6 | 0.75 | 0.875 | 1.00 | 1.125 | 1.25 | 1.375 | 1.50 | 1.75 | 2.00 | 2.25 | 2.50 |
| L＞6 | 1.00 | 1.125 | 1.25 | 1.375 | 1.50 | 1.625 | 1.75 | 2.00 | 2.25 | 2.50 | 2.75 | |
| r | max | 0.025 | 0.025 | 0.025 | 0.025 | 0.025 | 0.045 | 0.045 | 0.045 | 0.065 | 0.095 | 0.095 |
| min | 0.015 | 0.015 | 0.015 | 0.015 | 0.015 | 0.020 | 0.020 | 0.020 | 0.040 | 0.060 | 0.060 | |
Technical Data provided by Fastener Planet
| Thread Size (d) | 1-1/4 | 1-3/8 | 1-1/2 | 1-5/8 | 1-3/4 | 1-7/8 | 2 | 2-1/4 | 2-1/2 | 2-3/4 | 3 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ds | max | 1.250 | 1.375 | 1.500 | 1.625 | 1.750 | 1.875 | 2.000 | 2.250 | 2.500 | 2.750 | 3.000 |
| min | 1.239 | 1.363 | 1.488 | 1.613 | 1.738 | 1.863 | 1.988 | 2.238 | 2.488 | 2.738 | 2.988 | |
| s | Basic | 1-7/8 | 2-1/16 | 2-1/4 | 2-7/16 | 2-5/8 | 2-13/16 | 3 | 3-3/8 | 3-3/4 | 4-1/8 | 4-1/2 |
| max | 1.875 | 2.062 | 2.250 | 2.438 | 2.625 | 2.812 | 3.000 | 3.375 | 3.750 | 4.125 | 4.500 | |
| min | 1.812 | 1.994 | 2.175 | 2.356 | 2.538 | 2.719 | 2.900 | 3.262 | 3.625 | 3.988 | 4.350 | |
| e | max | 2.165 | 2.382 | 2.598 | 2.815 | 3.031 | 3.248 | 3.464 | 3.897 | 4.330 | 4.763 | 5.196 |
| min | 2.066 | 2.273 | 2.480 | 2.686 | 2.893 | 3.099 | 3.306 | 3.719 | 4.133 | 4.546 | 4.959 | |
| k | Basic | 25/32 | 27/32 | 15/16 | 1 | 1-3/32 | 1-5/32 | 1-7/32 | 1-3/8 | 1-17/32 | 1-11/16 | 1-7/8 |
| max | 0.813 | 0.878 | 0.974 | 1.038 | 1.134 | 1.198 | 1.263 | 1.423 | 1.583 | 1.744 | 1.935 | |
| min | 0.749 | 0.810 | 0.902 | 0.962 | 1.054 | 1.114 | 1.175 | 1.327 | 1.479 | 1.632 | 1.815 | |
| kw | min | 0.530 | 0.569 | 0.640 | 0.694 | 0.748 | 0.802 | 0.825 | 0.933 | 1.042 | 1.151 | 1.290 |
| b | L≤6 | 2.75 | 3.00 | 3.25 | 3.50 | 3.75 | 4.00 | 4.25 | / | / | / | / |
| L＞6 | 3.00 | 3.25 | 3.50 | 3.75 | 4.00 | 4.25 | 4.50 | 5.00 | 5.50 | 6.00 | 6.50 | |
| r | max | 0.095 | 0.095 | 0.095 | – | 0.095 | – | 0.095 | 0.095 | 0.095 | 0.095 | 0.095 |
| min | 0.060 | 0.060 | 0.060 | – | 0.060 | – | 0.060 | 0.060 | 0.060 | 0.060 | 0.060 | |
Technical Data provided by Fastener Planet