ASME B18.2.1 Hex Bolt Dimensions

ASTM A193 Grade B7 Specifications

ASME B18.2.1 Hex Bolts

ASME B18.2.1 Hex Bolts

ASME B18.2.1 Hex Bolt Dimensions (Imperial)

Nominal Size or Basic product Diameter (Inches) 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 inches & Shorter Over 6 inches
Max. Min. Basic Max. Min. Max. Min. Basic Max. Min. Max. Min. Nom. Nom.
1/4"
0.2500
0.260 0.237 7/16" 0.438 0.425 0.505 0.484 11/64" 0.188 0.150 0.03 0.01 0.750 1.000
5/16"
0.3125
0.324 0.298 1/2" 0.500 0.484 0.577 0.552 7/32" 0.235 0.195 0.03 0.01 0.875 1.125
3/8"
0.3750
0.388 0.360 9/16" 0.562 0.544 0.650 0.620 1/4" 0.268 0.226 0.03 0.01 1.000 1.250
7/16"
0.4375
0.452 0.421 5/8" 0.625 0.603 0.722 0.687 19/64" 0.316 0.272 0.03 0.01 1.125 1.375
1/2"
0.5000
0.515 0.482 3/4" 0.750 0.725 0.866 0.826 11/32" 0.364 0.302 0.03 0.01 1.250 1.500
5/8"
0.6250
0.642 0.605 15/16" 0.938 0.906 1.083 1.033 27/64" 0.444 0.378 0.06 0.02 1.500 1.750
3/4"
0.7500
0.768 0.729 1-1/8" 1.125 1.088 1.299 1.240 1/2" 0.524 0.455 0.06 0.02 1.750 2.000
7/8"
0.8750
0.895 0.852 1-5/16" 1.312 1.269 1.516 1.447 37/64" 0.604 0.531 0.06 0.02 2.000 2.250
1"
1.0000
1.022 0.976 1-1/2" 1.500 1.450 1.732 1.653 43/64" 0.700 0.591 0.09 0.03 2.250 2.500
1-1/8"
1.1250
1.149 1.098 1-11/16" 1.688 1.631 1.949 1.859 3/4" 0.780 0.658 0.09 0.03 2.500 2.750
1-1/4"
1.2500
1.277 1.223 1-7/8" 1.875 1.812 2.165 2.066 27/32" 0.876 0.749 0.09 0.03 2.750 3.000
1-3/8"
1.3750
1.404 1.345 2-1/16" 2.062 1.994 2.382 2.273 29/32" 0.940 0.810 0.09 0.03 3.000 3.250
1-1/2"
1.5000
1.531 1.470 2-1/4" 2.250 2.175 2.598 2.480 1" 1.036 0.902 0.09 0.03 3.250 3.500
1-5/8"
1.6250
1.658 1.591 2-7/16" 2.438 2.356 2.815 2.616 1-3/32" 1.116 0.978 0.09 0.03 3.500 3.750
1-3/4"
1.7500
1.785 1.716 2-5/8" 2.625 2.538 3.031 2.893 1-5/32" 1.196 1.054 0.12 0.04 3.750 4.000
1-7/8"
1.8750
1.912 1.839 2-13/16" 2.812 2.719 3.248 3.099 1-1/4" 1.276 1.130 0.12 0.04 4.000 4.250
2"
2.0000
2.039 1.964 3" 3.000 2.9000 3.464 3.306 1-11/32" 1.388 1.175 0.12 0.04 4.250 4.500
2 1/4"
2.2500
2.305 2.214 3-3/8" 3.375 3.262 3.897 3.719 1-1/2" 1.548 1.327 0.19 0.06 4.750 5.000
2 1/2"
2.5000
2.559 2.461 3-3/4" 3.750 3.625 4.330 4.133 1-21/32" 1.708 1.479 0.19 0.06 5.250 5.500
2-3/4"
2.7500
2.827 2.711 4-1/8" 4.125 3.988 4.763 4.546 1-13/16" 1.869 1.632 0.19 0.06 5.750 6.000
3"
3.0000
3.081 2.961 4-1/2" 4.500 4.350 5.196 4.959 2" 2.060 1.815 0.19 0.06 6.250 6.500
3-1/4"
3.2500
3.335 3.210 4-7/8" 4.875 4.712 5.629 5.372 2-3/16" 2.251 1.936 0.19 0.06 6.750 7.000
3-1/2"
3.5000
3.589 3.461 5-1/4" 5.250 5.075 6.062 5.786 2-5/16" 2.380 2.057 0.19 0.06 7.250 7.500
3-3/4"
3.7500
3.858 3.726 5-5/8" 5.625 5.437 6.495 6.198 2-1/2" 2.572 2.241 0.19 0.06 7.750 8.000
4"
4.0000
4.111 3.975 6" 6.000 5.800 6.928 6.612 2-11/16" 2.764 2.424 0.19 0.06 8.250 8.500

ASTM A193 Grade B7 Fastener Coatings