Screw Sizes Explained: #8, #12, and 14 Diameter Specifications

Understanding Screw Sizes and Numbering

Screw sizes are commonly identified by numbers such as #8, #12, or 14. These numbers correspond to standardized diameter measurements established by the Unified Thread Standard (UTS) system. Knowing the correct size is crucial for selecting screws that fit properly in wood, metal, or other materials.

In addition to diameter, screws are also characterized by thread pitch, head type, and length. Combining these specifications ensures both secure fastening and structural integrity.

What Size Is a #12 Screw?

A #12 screw is a common large-diameter screw used in heavy-duty applications such as construction, cabinetry, and industrial projects. Its diameter provides high holding power and stability when fastened into wood or plastic.

The standard diameter of a #12 screw is approximately 0.216 inches (5.49 mm). This measurement refers to the major diameter of the screw threads, which is the widest part of the screw.

What Is the Diameter of a 14 Screw?

A 14 screw, sometimes written as #14, is slightly larger than a #12 screw and is designed for very heavy-duty fastening tasks. It is commonly used in structural framing, decking, and situations that require maximum holding strength.

The diameter of a 14 screw is approximately 0.242 inches (6.15 mm). This larger diameter allows for increased torque resistance and prevents stripping when driven into dense materials.

What Size Is a #8 Screw?

A #8 screw is a medium-sized screw widely used for general-purpose applications in woodworking, cabinetry, and home improvement projects. It balances strength and ease of installation for everyday fastening needs.

The standard diameter of a #8 screw is approximately 0.164 inches (4.17 mm). It is ideal for connecting pieces without requiring oversized holes or specialized drilling equipment.

Common Screw Diameter Comparison

Choosing the Right Screw for Your Project

Selecting the correct screw size depends on the material, load requirements, and installation conditions. Using a screw that is too small can lead to stripping or weak connections, while an oversized screw may damage the material.

For general projects, #8 screws are versatile and easy to work with. For heavier-duty applications requiring high strength, #12 and #14 screws are recommended. Always consult the material specifications and manufacturer guidelines before choosing the appropriate screw.