Hex Head Cap Screws
Fully threaded hex heads with a robust design for industrial applications.
Manufactured to ASME B18.2.1 with washer-face bearing surface, in all stocked grades.
Specifications & technical data.
We manufacture and stock hex head cap screws to ASME B18.2.1 — cut or rolled thread, in every grade from SAE Gr.5 and Gr.8 through B7, B16 and the stainless and nickel alloys. The full dimensional table is below; nonstandard lengths and materials are machined to order.
Download our hex head cap screw dimensioning table (PDF)
| Nominal Size (Basic Product Diameter) | E | F | G | H | J | LT | Y | FIM | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Body Diameter | Width Across Flats | Width Across Corners | Head Height | Minimum Wrenching Height | Thread Length for Screw Lengths L | Transition Thread Length (Max.) | Max. Total Runout of Bearing Surface | |||||||||
| Basic | Max. | Min. | Basic | Max. | Min. | Max. | Min. | Basic | Max. | Min. | 6 in. & Shorter | Over 6 in. | ||||
| 1/4" | 0.2500 | 0.2500 | 0.2450 | 7/16 | 0.438 | 0.428 | 0.505 | 0.488 | 5/32 | 0.163 | 0.150 | 0.106 | 0.750 | 1.000 | 0.250 | 0.010 |
| 5/16" | 0.3125 | 0.3125 | 0.3065 | 1/2 | 0.500 | 0.489 | 0.577 | 0.557 | 13/64 | 0.211 | 0.195 | 0.140 | 0.875 | 1.125 | 0.278 | 0.011 |
| 3/8" | 0.3750 | 0.3750 | 0.3690 | 9/16 | 0.562 | 0.551 | 0.650 | 0.628 | 15/64 | 0.243 | 0.226 | 0.160 | 1.000 | 1.250 | 0.312 | 0.012 |
| 7/16" | 0.4375 | 0.4375 | 0.4305 | 5/8 | 0.625 | 0.612 | 0.722 | 0.698 | 9/32 | 0.291 | 0.272 | 0.195 | 1.125 | 1.375 | 0.357 | 0.013 |
| 1/2" | 0.5000 | 0.5000 | 0.4930 | 3/4 | 0.750 | 0.736 | 0.866 | 0.840 | 5/16 | 0.323 | 0.302 | 0.215 | 1.250 | 1.500 | 0.385 | 0.014 |
| 9/16" | 0.5625 | 0.5625 | 0.5545 | 13/16 | 0.812 | 0.798 | 0.938 | 0.910 | 23/64 | 0.371 | 0.348 | 0.250 | 1.375 | 1.625 | 0.417 | 0.015 |
| 5/8" | 0.6250 | 0.6250 | 0.6170 | 15/16 | 0.938 | 0.922 | 1.083 | 1.051 | 25/64 | 0.403 | 0.378 | 0.269 | 1.500 | 1.750 | 0.455 | 0.017 |
| 3/4" | 0.7500 | 0.7500 | 0.7410 | 1-1/8 | 1.125 | 1.100 | 1.299 | 1.254 | 15/32 | 0.483 | 0.455 | 0.324 | 1.750 | 2.000 | 0.500 | 0.020 |
| 7/8" | 0.8750 | 0.8750 | 0.8660 | 1-5/16 | 1.312 | 1.285 | 1.516 | 1.465 | 35/64 | 0.563 | 0.531 | 0.378 | 2.000 | 2.250 | 0.556 | 0.023 |
| 1" | 1.0000 | 1.0000 | 0.9900 | 1-1/2 | 1.500 | 1.469 | 1.732 | 1.675 | 39/64 | 0.627 | 0.591 | 0.416 | 2.250 | 2.500 | 0.625 | 0.026 |
| 1-1/8" | 1.1250 | 1.1250 | 1.1140 | 1-11/16 | 1.688 | 1.631 | 1.949 | 1.859 | 11/16 | 0.718 | 0.658 | 0.461 | 2.500 | 2.750 | 0.714 | 0.029 |
| 1-1/4" | 1.2500 | 1.2500 | 1.2390 | 1-7/8 | 1.875 | 1.812 | 2.165 | 2.066 | 25/32 | 0.813 | 0.749 | 0.530 | 2.750 | 3.000 | 0.714 | 0.033 |
| 1-3/8" | 1.3750 | 1.3750 | 1.3630 | 2-1/16 | 2.062 | 1.994 | 2.382 | 2.273 | 27/32 | 0.878 | 0.810 | 0.569 | 3.000 | 3.250 | 0.833 | 0.036 |
| 1-1/2" | 1.5000 | 1.5000 | 1.4880 | 2-1/4 | 2.250 | 2.175 | 2.598 | 2.480 | 15/16 | 0.974 | 0.902 | 0.640 | 3.250 | 3.500 | 0.833 | 0.039 |
| 1-5/8" | 1.6250 | 1.6250 | 1.6130 | 2-7/16 | 2.438 | 2.356 | 2.815 | 2.686 | 1 | 1.038 | 0.962 | 0.694 | 3.500 | 3.750 | 0.909 | 0.043 |
| 1-3/4" | 1.7500 | 1.7500 | 1.7380 | 2-5/8 | 2.625 | 2.538 | 3.031 | 2.893 | 1-3/32 | 1.134 | 1.054 | 0.748 | 3.750 | 4.000 | 1.000 | 0.046 |
| 1-7/8" | 1.8750 | 1.8750 | 1.8630 | 2-13/16 | 2.812 | 2.719 | 3.248 | 3.099 | 1-5/32 | 1.198 | 1.114 | 0.802 | 4.000 | 4.250 | 1.000 | 0.049 |
| 2" | 2.0000 | 2.0000 | 1.9880 | 3 | 3.000 | 2.900 | 3.464 | 3.306 | 1-7/32 | 1.263 | 1.175 | 0.825 | 4.250 | 4.500 | 1.111 | 0.052 |
| 2-1/4" | 2.2500 | 2.2500 | 2.2380 | 3-3/8 | 3.375 | 3.262 | 3.897 | 3.719 | 1-3/8 | 1.423 | 1.327 | 0.933 | … | 5.000 | 1.111 | 0.059 |
| 2-1/2" | 2.5000 | 2.5000 | 2.4880 | 3-3/4 | 3.750 | 3.625 | 4.330 | 4.133 | 1-17/32 | 1.583 | 1.479 | 1.042 | … | 5.500 | 1.250 | 0.065 |
| 2-3/4" | 2.7500 | 2.7500 | 2.7380 | 4-1/8 | 4.125 | 3.988 | 4.763 | 4.546 | 1-11/16 | 1.744 | 1.632 | 1.151 | … | 6.000 | 1.250 | 0.072 |
| 3" | 3.0000 | 3.0000 | 2.9880 | 4-1/2 | 4.500 | 4.350 | 5.196 | 4.959 | 1-7/8 | 1.935 | 1.815 | 1.290 | … | 6.500 | 1.250 | 0.079 |
All dimensions in inches, per ASME B18.2.1-2012. L = nominal screw length; LG max = L - LT. Confirm requirements with our estimating team.
Standards.
What are hex head cap screws?
Hex head cap screws are the wrench-driven workhorse of bolted joints: a six-sided head, a washer-faced bearing surface, and a chamfered point, made to the tighter body and head tolerances of ASME B18.2.1. They assemble into tapped holes or with a nut, and the controlled underhead surface gives consistent preload when torqued.
- External hex drive — driven with a wrench or socket
- Washer-faced bearing surface for consistent torque-tension
- Tighter body, head and length tolerances than a hex bolt
- Cut or rolled thread, partial or full length
- Every grade from Gr.5 / Gr.8 to B7, B16 and exotics
Hex cap screws vs. hex bolts
The two look alike but are held to different rules. A hex cap screw carries closer tolerances, a washer face under the head, and a chamfered point — made for machined and tapped assemblies. A hex bolt runs looser tolerances with a plain flat bearing surface, sized for structural work where the nut does the fitting. If your print says cap screw, a bolt is not a substitute.
Other names
- Hex cap screws
- Hexagon head cap screws
- Finished hex bolts
- HHCS
- Hex machine bolts (loosely)
Industries & applications
Oil & Gas
- Applications: skid packages, pump baseplates, non-pressure flanged equipment
- Materials: A193 B7, A320 L7, SAE Gr.8, super duplex
Power Generation
- Applications: structural frames, turbine auxiliaries, high-temperature service
- Materials: A193 B16, A453 660, stainless grades
Waterworks & Renewables
- Applications: treatment plants, tower internals, galvanized structural assemblies
- Materials: hot-dip galvanized alloy, 316L, duplex 2205
Tips for purchasing
- Check grip against thread length — LT in the table sets how much of your length is threaded; ask for full thread (tap bolts) when you need it.
- Name the grade and the finish together — plain, zinc, hot-dip galvanized or PTFE-coated changes fit and torque.
- Cut vs. rolled thread matters for fatigue service — tell us the application and we will steer you.
- Full material test reports and heat traceability come standard from our shop.
Materials.
Representative capabilities — every item is manufactured or certified to your specification. Confirm requirements with our estimating team.
