How Many Types of Bolts and Nuts Are There?

When it comes to construction, engineering, or even simple DIY projects, bolts and nuts are essential components that hold things together. Knowing the different types of bolts and nuts available can help you choose the right ones for your projects.

In this article, we will explore the wide range of bolts and nuts, their uses, and the factors to consider when selecting the appropriate fasteners.

Types of Bolts and Nuts

How Many Types of Bolts and Nuts Are There?

Bolts and nuts can be classified into different categories based on their design, head shape, threading, and application. Let’s delve into the various types in detail:

1. Anchor Bolts

Anchor bolts are specifically designed to secure structures to concrete or masonry. They have threaded ends and are embedded in the material during construction. 

Anchor bolts provide stability and prevent structural movement, making them crucial in applications like building foundations, bridges, and machinery installations.

2. Carriage Bolts

Carriage bolts, also known as coach bolts, feature a round, domed head and a square or ribbed shoulder beneath it. The square shoulder helps to prevent the bolt from rotating when tightened. 

These bolts are commonly used in woodworking and outdoor construction projects, such as deck building and fence installation.

3. Hex Bolts

Hex bolts, also called hexagon bolts or machine bolts, have a hexagonal head and a threaded shaft. They are widely used in various industries and applications, including automotive, machinery, and structural assemblies. 

Hex bolts offer high tensile strength and are available in different grades and materials to suit specific requirements.

4. Lag Bolts

Lag bolts, often referred to as lag screws, are heavy-duty fasteners with coarse threading and a hexagonal head. They are primarily used to secure wood to wood or attach heavy objects to wood surfaces. 

Lag bolts are commonly employed in construction, furniture assembly, and outdoor projects like deck framing and timber connections.

5. U-Bolts

U-bolts are named for their U-shaped design and are used to secure pipes, poles, and other cylindrical objects to flat surfaces. 

They have threaded ends on both sides and are secured with nuts. U-bolts find applications in the automotive, plumbing, and construction industries.

6. Eye Bolts

Eye bolts have a circular loop or “eye” at the top end, making them ideal for attaching ropes, cables, or chains for lifting or hanging purposes. 

They are commonly used in rigging, marine, and outdoor applications. Eye bolts should be carefully chosen based on their load capacity and the intended use.

7. Stud Bolts

Stud bolts are fully threaded rods without heads. They are used in situations where a bolted connection is required on both ends, such as flange connections in pipelines or machinery. 

Stud bolts are commonly utilized in oil and gas, petrochemical, and power generation industries.

8. Wing Nuts

Wing nuts are nuts with two large projecting wings on opposite sides, allowing for easy hand tightening and loosening without the need for tools. 

They are commonly used in applications where frequent adjustments or removals are required, such as temporary fixings, furniture assembly, and light-duty fastening.

9. Cap Nuts

Cap nuts, also known as acorn nuts or dome nuts, have a domed top that covers the threaded end of a bolt. They provide a finished appearance, protect against injury from exposed threads, and prevent loosening due to vibrations. 

Cap nuts are commonly used in decorative applications, automotive wheel covers, and architectural structures.

10. Lock Nuts

Lock nuts, as the name suggests, are designed to prevent loosening under vibration or torque. They have a specialized design that adds friction to the fastening mechanism, ensuring a secure connection. 

Lock nuts are commonly used in machinery, automotive, and aerospace industries.


In conclusion, the world of bolts and nuts is diverse, with a wide array of options available for different applications. From anchor bolts for securing structures to lock nuts for preventing loosening, each type has its unique characteristics and purpose. 

By selecting the right bolts and nuts, you can enhance the structural integrity and longevity of your constructions or assemblies.


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