Hex Head Bolts
Versatile fasteners with hexagonal heads used across every industry we serve.
Part-threaded hex bolts in the full range of grades and finishes, imperial and metric.
Specifications & technical data.
Hex head bolts to ASME B18.2.1 — the structural pattern with a plain bearing surface and full-size or reduced body, in every grade from A307 and Gr.5 through B7 and the stainless alloys, plain or hot-dip galvanized.
Download our hex head bolt dimensioning table (PDF)
| Nominal Size or Product Diameter | E | F | G | H | R | LT | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Full-size Body Diameter | Width Across Flats | Width Across Corners | Height | Radius of Fillet | Nominal Thread Length for Bolt Lengths | ||||||||||
| Max. | Min. | Basic | Max. | Min. | Max. | Min. | Basic | Max. | Min. | Max. | Min. | 6 in. & Shorter | Over 6 in. | ||
| 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 | 2.900 | 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 |
All dimensions in inches, per ASME B18.2.1-2012. L = nominal bolt length. Confirm requirements with our estimating team.
Standards.
What are hex head bolts?
Hex head bolts are the structural workhorse: a six-sided head with a plain bearing surface, driven with a wrench and made up with a nut. They run to looser tolerances than a hex cap screw — by design — because in structural and general-purpose joints the nut does the fitting, not a tapped hole.
- Plain (non–washer-faced) bearing surface
- Full-size or reduced body
- Made up with a nut — the classic bolted joint
- Plain, zinc or hot-dip galvanized finishes
- A307, SAE grades, B7 and stainless
Hex bolts vs. hex cap screws
Same silhouette, different rulebook. The bolt carries wider tolerances and a plain bearing face for structural work with a nut; the cap screw carries close tolerances and a washer face for machined assemblies. Prints that say bolt mean bolt — and the price and availability often favor it.
Other names
- Hexagon bolts
- Hex bolts
- Machine bolts
- Structural bolts (loosely)
Tips for purchasing
- Thread length follows bolt length — LT in the table; ask for full thread (tap bolts) when the grip is short.
- Galvanized bolts need oversize-tapped nuts — order them as a set.
- Match the washer and nut grade to the bolt — we certify assemblies together.
- Full material test reports and heat traceability come standard.
Materials.
Representative capabilities — every item is manufactured or certified to your specification. Confirm requirements with our estimating team.
