When working on DIY projects around the home or in the garage, having the right fasteners can make all the difference. Two of the most common types of fasteners are hex bolts and carriage bolts. But when should you use one versus the other? In this article, we’ll compare hex bolts and carriage bolts, so you can determine which is the best choice for your specific needs.

What is a Hex Bolt?

A hex bolt, sometimes called a hex cap screw, has a hexagonal head and machine threads that screw into a tapped hole. The six-sided head allows you to easily grip and turn the bolt with a wrench. Hex bolts are used in all sorts of applications from machinery to construction projects. They come in different sizes and are made from various materials like steel, stainless steel, brass, and aluminum.



What is a Carriage Bolt?

A carriage bolt has a domed head instead of a hex head. But it also has machine threads like a hex bolt. The key difference is that a carriage bolt has a square neck under the domed head. This square neck grips into the wood, preventing the bolt from spinning when you tighten a nut on the protruding threads. Carriage bolts are designed specifically for woodworking applications.

hex bolts vs carriage bolts

Comparing Strength and Use

When deciding between hex bolts vs carriage bolts, you first need to consider the purpose of your project. Here’s how the strengths and uses of these two popular fasteners compare:

  • Shear and Tensile Strength: Hex bolts are stronger than carriage bolts in terms of shear strength and tensile strength. The hex head allows more torque to be applied when tightening the bolt. So for applications where high strength is needed, hex bolts are the better choice.
  • Vibration Resistance: The square neck under the head of a carriage bolt helps lock it in place against vibration. So for applications like handrails or furniture that may shake or move, carriage bolts are less likely to loosen over time.
  • Gripping Strength: Carriage bolts grip well into wood without spinning, making them ideal for woodworking. Hex bolts do not have the same gripping capability, so they would spin in wood when tightening unless secured with a washer or other method.
  • Assembly: Carriage bolts are quick and easy to install in wood with just a wrench. Hex bolts require first drilling and tapping a hole to thread them in. So hex bolts take more time and tools for assembly.
  • Appearance: The domed head of a carriage bolt has a cleaner, more finished look if the head is exposed. A hex bolt has a more industrial look.

Common Applications

Now let’s look at some of the most common uses for each type of fastener:

When to Use Hex Bolts

  • Metal fabrication projects
  • Machinery and equipment
  • Automotive applications
  • Construction projects like railings or steps
  • Any application needing high strength
  • Fastening metal to metal or metal to concrete

When to Use Carriage Bolts

  • Woodworking projects
  • Furniture that may be moved or shaken
  • Dock pilings or wood exposed to water
  • Deck railing posts
  • Fencing or sign posts
  • Doors, shelves, and other decorative woodwork

Hex Bolts vs Carriage Bolts: Making the Best Choice

When choosing fasteners for your DIY project, consider these key factors:

  • What materials are you fastening together – wood, metal, or concrete?
  • Does it need high strength and torque resistance?
  • Will it be subjected to vibration or movement?
  • Do you need speed and ease of installation?
  • What will the exposed heads look like?

In summary:

  • Hex bolts are best for metal, high strength, machined applications. The hex head resists vibration but has an industrial look.
  • Carriage bolts are ideal for quickly fastening wood while resisting spin out. The domed head provides a finished, decorative look.

No matter your project, Jmet Corp has you covered with a huge selection of hex bolts and carriage bolts in all sizes and materials. Contact us today to order exactly what you need or get help choosing the optimal fasteners. Our team is ready to assist with all your DIY questions and hardware needs!

Frequently Asked Questions

What’s the difference between a hex bolt and a hex cap screw?

There is no actual difference – hex bolt and hex cap screw are two names for the same type of fastener. The 6-sided hexagonal head allows tightening with a wrench.

What materials are carriage bolts available in?

Most carriage bolts are steel or stainless steel. However, you can sometimes find them in aluminum, brass, or other metals. The square neck and domed head differentiate them from hex bolts.

Can I use a carriage bolt in metal instead of wood?

You could, but a hex bolt would be the better choice for metal applications. Without the wood to grip onto, the square neck of a carriage bolt serves no purpose when used in metal.

Are carriage bolts and lag bolts the same thing?

No, lag bolts have thicker, coarser threads meant for fastening wood by screwing into it. Carriage bolts have smoother machine threads like hex bolts and are secured with a nut.

What size hex bolt and carriage bolt is best for wood projects?

For most furniture and woodworking applications, sizes between 1/4″-5/16″ diameter provide a good balance of strength without being oversized. Match the pilot hole size to the bolt diameter.

Can I use washers with carriage bolts or hex bolts?

Yes, washers help distribute load pressure and protect surfaces. Use a washer under the bolt head or under the nut once threaded on. Avoid over-tightening.


Whether you are building a workbench, manufacturing equipment, constructing a railing, or completing any other DIY project, having the right bolts makes the job easier and improves durability of the finished product. Consider where the bolts will be used, the required strength, vibration resistance, speed of installation, appearance, and other factors. Hex bolts are best for metal jobs demanding high strength, while carriage bolts excel at quickly fastening wood while preventing spin out.

Contact the team at Jmet Corp to order the exact type, size, and quantity of hex bolts or carriage bolts needed for your next DIY or commercial project. We offer hassle-free ordering, quick shipping, and competitive pricing on all your fastener needs. Our hardware experts are also available to provide guidance if you have any questions about selecting the optimal bolts. Rely on Jmet Corp for all the brackets, nuts, washers, screws, bolts, and specialty hardware that brings your project vision to life!