Hex bolts, also known as hexagonal head bolts, are threaded machine bolts used with a nut or in a tapped hole. As the name suggests, hex head bolts are hexagonal heads (6 sides) made from grade 2 galvanized steel, 316/304 stainless steel, and grade 5 zinc plated steel.

Hex Head Bolts


Hex head bolts are designed to secure objects within or against other objects for a non-loosening hold. Applications for a hex bolt include fastening steel to steel, wood to wood, and other materials found on construction for projects such as highway structures, bridges, and buildings.


The Hex bolts allow for greater torque than traditional circular screws and tend to spin as you tighten and loosen them, making the need to hold with a wrench or socket. Hex bolts are commonly installed and removed with socket wrenches.


Hex head bolts come in two styles fully threaded and partially threaded. A fully threaded hex head bolt is used when it is matched up to a fully threaded hole. Partially threaded bolts are more rigid and have an unthreaded area under their head to allow for more holding strength when force is applied to the structure being secured.


Hex Head Bolts are not Hex Cap Screws 

Mistaking a hex cap screw for a hex bolt is very common, but the two fasteners differ in many ways, including how they are used and installed.

  • Hex bolts are installed by turning a nut to tighten the fastener.
    Hex cap screws are installed into tapped holes by turning the head to assemble and tighten.

  • Hex bolts have neither the washer face nor chamfered point.
    Hex cap screws feature a washer face on the bearing surface and the chamfered point.

  • Hex bolts are often used in the construction industry, where mechanical properties are more critical than dimensional tolerances.

    Hex cap screws are commonly used for precision applications where tight tolerance is required.

Hex Head Bolts Head & Thread Dimensions

Technical dimensional information for the head & threads of hex cap screws of all grades & materials. Technical dimensions include body diameter, width across the flats, width across the corners, head height & thread length.


The standard thread length of a hex head bolt:

Bolt lengths ≤ 6″: Thread length = (2 X diameter) + 1/4″
Bolt lengths > 6″: Thread length = (2 X diameter) + 1/2″
Note: Most stock hex bolts 10″ and longer will have 6″ of thread.

The basic specs of a hex head bolt:

Diameters: 1/2 – 1″
Grade: ASTM A307 Grade A, F1554 Grade 36
Lengths: 30″ maximum
Finish: Plain and hot dip galvanized



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