HEX BOLT SIZES CHART

Hex bolts sizes chart according to ASME B18.2.1 for inch series bolts and screws. All dimensions are given in inches. Hex bolt sizes between 1/4 to 4 inches are given below.

Hex Bolt Dimensions
Nominal
 Size
Basic
Product
Diameter
E F G H R LT
6 in and
Shorter
Over
6 in.
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


Nominal
 Size
Basic
Product
Diameter
E F G H R LT
6 in and
Shorter
Over
6 in.
Max. Min Basic Max Min Max. Min. Basic Max. Min. Max. Min. Nom. Nom.
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 2.900 3.464 3.306 1 11/32 1.388 1.175 0.12 0.04 4.250 4.500

Nominal
 Size
Basic
Product
Diameter
E F G H R LT
6 in and
Shorter
Over
6 in.
Max. Min Basic Max Min Max. Min. Basic Max. Min. Max. Min. Nom. Nom.
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

F - Width Across Flats, E - Full-Size Body Diameter, G - Width Across Corners, H - Head Height, R - Radius of fillet, L LT - Thread Length for Bolt Lengths

Supplements:

Reference:

  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) . Machinery's Handbook . 30th edition.  Industrial Press Inc. , pp 1591
  • ASME B18.2.1-2010, Square, Hex, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex, Hex Flange, Lobed Head, and Lag Screws (Inch Series)