Hex Bolt vs. Other Bolt Types

A hex bolt is the most widely used bolt type. It has a six-sided (hexagonal) head that is tightened with a wrench or socket. But it is not the only option. Here is how hex bolts compare to other common types.

Hex Bolt

External hex head, driven with a wrench or socket. Used in construction, machinery, and general assembly. Available in full thread and partial thread. The standard choice when you need a strong, accessible bolt head.

Hex Lag Bolt

Similar hex head, but with a pointed wood-screw tip and coarser threads. Designed to fasten into wood or lag shields in masonry. Used for deck framing, ledger boards, and heavy timber connections. Not paired with a nut — driven directly into the material.

Carriage Bolt

Round domed head with a square shoulder under the head that prevents the bolt from spinning in a round hole. Used in wood-to-wood or wood-to-metal connections where a smooth, tamper-resistant head is desired — common in decks, fences, and playground equipment.

Socket Head Cap Screw

Cylindrical head with an internal hex (Allen) drive. Provides high clamping force in a compact profile. Used in machinery, tooling, and precision assemblies where clearance is tight.

Which Should You Choose?

• General purpose: hex bolt
• Wood fastening: hex lag bolt
• Smooth / tamper-resistant head: carriage bolt
• Tight clearance / machinery: socket head cap screw