ASME B18.2.1 Standard Dimensions for Hex Bolts
| Nominal Size or Basic product Diameter |
Full-Size Body Diameter, E |
Width Across Flats, F |
Width Across Corners, G |
Head Height, H |
Radius of Fillet, R |
Thread Length for Bolt Lengths, LT |
| 6 in. & Shorter |
Over 6 in. |
| Max. |
Min. |
Max. |
Min. |
Max. |
Min. |
Max. |
Min. |
Max. |
Min. |
Nom. |
Nom. |
| 1/4 |
0.2500 |
0.260 |
0.237 |
0.438 |
0.425 |
0.505 |
0.484 |
0.188 |
0.150 |
0.03 |
0.01 |
0.750 |
1.000 |
| 5/16 |
0.3125 |
0.324 |
0.298 |
0.500 |
0.484 |
0.577 |
0.552 |
0.235 |
0.195 |
0.03 |
0.01 |
0.875 |
1.125 |
| 3/8 |
0.3750 |
0.388 |
0.360 |
0.562 |
0.544 |
0.650 |
0.620 |
0.268 |
0.226 |
0.03 |
0.01 |
1.000 |
1.250 |
| 7/16 |
0.4375 |
0.452 |
0.421 |
0.625 |
0.603 |
0.722 |
0.687 |
0.316 |
0.272 |
0.03 |
0.01 |
1.125 |
1.375 |
| 1/2 |
0.5000 |
0.515 |
0.482 |
0.750 |
0.725 |
0.866 |
0.826 |
0.364 |
0.302 |
0.03 |
0.01 |
1.250 |
1.500 |
| 5/8 |
0.6250 |
0.642 |
0.605 |
0.938 |
0.906 |
1.083 |
1.033 |
0.444 |
0.378 |
0.06 |
0.02 |
1.500 |
1.750 |
| 3/4 |
0.7500 |
0.768 |
0.729 |
1.125 |
1.088 |
1.299 |
1.240 |
0.524 |
0.455 |
0.06 |
0.02 |
1.750 |
2.000 |
| 7/8 |
0.8750 |
0.895 |
0.852 |
1.312 |
1.269 |
1.516 |
1.447 |
0.604 |
0.531 |
0.06 |
0.02 |
2.000 |
2.250 |
| 1 |
1.0000 |
1.022 |
0.976 |
1.500 |
1.450 |
1.732 |
1.653 |
0.700 |
0.591 |
0.09 |
0.03 |
2.250 |
2.500 |
| 1 1/8 |
1.1250 |
1.149 |
1.098 |
1.688 |
1.631 |
1.949 |
1.859 |
0.780 |
0.658 |
0.09 |
0.03 |
2.500 |
2.750 |
| 1 1/4 |
1.2500 |
1.277 |
1.223 |
1.875 |
1.812 |
2.165 |
2.066 |
0.876 |
0.749 |
0.09 |
0.03 |
2.750 |
3.000 |
| 1 3/8 |
1.3750 |
1.404 |
1.345 |
2.062 |
1.994 |
2.382 |
2.273 |
0.940 |
0.810 |
0.09 |
0.03 |
3.000 |
3.250 |
| 1 1/2 |
1.5000 |
1.531 |
1.470 |
2.250 |
2.175 |
2.598 |
2.480 |
1.036 |
0.902 |
0.09 |
0.03 |
3.250 |
3.500 |
| 1 5/8 |
1.6250 |
1.658 |
1.591 |
2.438 |
2.356 |
2.815 |
2.616 |
1.116 |
0.978 |
0.09 |
0.03 |
3.500 |
3.750 |
| 1 3/4 |
1.7500 |
1.785 |
1.716 |
2.625 |
2.538 |
3.031 |
2.893 |
1.196 |
1.054 |
0.12 |
0.04 |
3.750 |
4.000 |
| 1 7/8 |
1.8750 |
1.912 |
1.839 |
2.812 |
2.719 |
3.248 |
3.099 |
1.276 |
1.130 |
0.12 |
0.04 |
4.000 |
4.250 |
| 2 |
2.000 |
2.039 |
1.964 |
3.000 |
2.9000 |
3.464 |
3.306 |
1.388 |
1.175 |
0.12 |
0.04 |
4.250 |
4.500 |
| 2 1/4 |
2.2500 |
2.305 |
2.214 |
3.375 |
3.262 |
3.897 |
3.719 |
1.548 |
1.327 |
0.19 |
0.06 |
4.750 |
5.000 |
| 2 1/2 |
2.5000 |
2.559 |
2.461 |
3.750 |
3.625 |
4.330 |
4.133 |
1.708 |
1.479 |
0.19 |
0.06 |
5.250 |
5.500 |
| 2 3/4 |
2.7500 |
2.827 |
2.711 |
4.125 |
3.988 |
4.763 |
4.546 |
1.869 |
1.632 |
0.19 |
0.06 |
5.750 |
6.000 |
| 3 |
3.000 |
3.081 |
2.961 |
4.500 |
4.350 |
5.196 |
4.959 |
2.060 |
1.815 |
0.19 |
0.06 |
6.250 |
6.500 |
| 3 1/4 |
3.2500 |
3.335 |
3.210 |
4.875 |
4.712 |
5.629 |
5.372 |
2.251 |
1.936 |
0.19 |
0.06 |
6.750 |
7.000 |
| 3 1/2 |
3.5000 |
3.589 |
3.461 |
5.250 |
5.075 |
6.062 |
5.786 |
2.380 |
2.057 |
0.19 |
0.06 |
7.250 |
7.500 |
| 3 3/4 |
3.7500 |
3.858 |
3.726 |
5.625 |
5.437 |
6.495 |
6.198 |
2.572 |
2.241 |
0.19 |
0.06 |
7.750 |
8.000 |
| 4 |
4.000 |
4.111 |
3.975 |
6.000 |
5.800 |
6.928 |
6.612 |
2.764 |
2.424 |
0.19 |
0.06 |
8.250 |
8.500 |
ASTM A193 Grade B8C Fastener Coatings
