ThePipingMart Blog Fasteners What is Hex Bolt? Properties, Dimensions and Uses

What is Hex Bolt? Properties, Dimensions and Uses

What is a Hex Bolt

Hexagon bolts, also known as hex cap screws and head bolts, are a fastener used to assemble two or more items. They are often found in construction projects and repairs but can also be used for other tasks, such as furniture assembly. Hexagonal bolts have many advantages over other fasteners, including their strength and versatility. Let’s take a closer look at what makes them so valuable.

Hex Bolt Properties

Compatibility with Nuts & Washers

Hexagonal bolts can be paired with nuts and washers to form secure connections between two components. This is because the shape of the bolt is designed to fit into the nut, creating a tight connection that won’t come undone easily. Additionally, using a washer on either side of the nut will ensure that the bolt doesn’t slip out when tightened. Not all screws can pair with nuts this way; some require specialized tools like thread lockers to create secure connections.

Tightening Ease & Strength

The six sides of the hexagonal bolt make it much easier to tighten than other types of fasteners, like round-headed screws or nails. The extra surface area allows you to use more force when tightening the bolt without risking it slipping out of place or becoming damaged by over-tightening. This makes hex cap screws ideal for applications that need strong connections that won’t come undone easily.

Strength & Durability

Hexagonal bolts are made from solid materials such as steel, stainless steel and brass, which means they are highly resistant to corrosion and wear and tear over time. This makes them an excellent choice for outdoor applications where they may be exposed to harsh weather conditions or lots of movement (e.g., machinery). Additionally, their shape creates strong joints that won’t come apart even when subjected to high levels of stress or vibration.

Hex Bolt Uses

Hexagonal bolts are quite useful as a fastening tool, often found in construction and DIY projects. The hexagonal head provides an easy-to-grip shape that helps to make installation or removal easier compared to other fasteners. Hex bolts can be used for wood and metal components, making them highly versatile. Moreover, hex bolts can form a tight fit with nuts and washers due to the flat sides of their heads, preventing them from becoming loose over time. Overall, their wide range of uses has made hexagonal bolts popular for various assembly purposes when precision is necessary.

Hex Bolt Dimensions

Hex Bolt dimensions

Hex Bolt Dimensions (ANSI B18.2.1-1996)
Size or Basic Diameter
Body Diameter
Width Across Corners (G) Head
Radius of Fillet (R) Thread
Max Min Basic Max Min Max Min Basic Max Min Max Min Basic (6 in. and shorter) Basic (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
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


Hexagon bolts offer several advantages over other types of fasteners – namely, their compatibility with nuts and washers, ease of tightening, strength and durability – making them an excellent choice for any project requiring secure connections between components that won’t come apart easily over time. Whether building something from scratch or performing repairs on existing items around your home or workplace, hex cap screws should always be at the top of your list!

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