Screw Head Types: Exploring the Varieties and What They Do

By: Contributors  | 
Person holding a dark colored screwdriver with red stripes on it.
A screwdriver as shown on a TLC program.

Screws are indispensable in both DIY projects and professional constructions. While it's easy to over look their heads, they play a crucial role in the success of any building project. And there are a lot of screw head types out there, each with specific names, designs, and applications.

If you're wading into the world of personal or professional construction and looking to build a toolset to be proud of, it's essential to have a broad understanding of different screw heads. In this article, we'll lay out the most common screw head types and when you'll need them during your project or on the job.


Understanding the Most Common Screw Head Types

Screws come in an array of head styles, each tailored to specific needs and applications. Among these, flat and oval heads stand out for their versatility and functionality. While flat head screws are prized for their ability to lie flush with the surface, oval head screws combine the benefits of flat heads with a slightly rounded top, providing a more decorative finish.

Another key player in this lineup is the trim head screw, a variant that offers a smaller head size, making it less conspicuous in projects where aesthetics are crucial. Meanwhile, the traditional slotted screws, with their simple yet effective design, remain a staple in many basic applications.


Understanding these common screw head types is essential for anyone delving into the world of DIY projects, carpentry, or construction. So, let's dive into the most frequently used screw head types!

Flat Head Screws: The Classics

The flat head screw, characterized by its flat top and conical shape, is one of the most common types. Ideal for applications where the screw needs to sit flush against the surface, they are often used in woodworking and cabinetry. The design allows for a tighter fit and a more aesthetic finish.

Phillips Head Screws: The Cross-Shaped Convenience

Phillips head screws, easily identifiable by their cross-shaped slot, offer a better grip for the screwdriver, reducing the chance of 'cam-out' (slipping). This design allows for higher torque to be applied, making them suitable for a wide range of applications, from electronics to construction.

Torx Head Screws: The Star Performers

Torx, or star head screws, are distinguished by their six-pointed star-shaped slot. This unique design provides an even distribution of force, reducing wear and tear. Torx screws are favored in automotive and electronic industries for their ability to withstand high torques and provide secure fastening.

Hex Cap Screws: The Wrench-Friendly Option

Hex head screws, known for their hexagonal shape, are designed to be driven by a wrench or a socket. This makes them ideal for situations where a screwdriver can't provide enough torque. Commonly used in machinery and large-scale construction, these screws offer robust fastening capabilities.

Robertson Head Screws: The Square Deal

Originating from Canada, the Robertson, or square head screws, feature a square-shaped indentation. This design allows for a higher torque without stripping the head, making them a popular choice in woodworking and decking. They provide a stable drive and are less prone to cam-out compared to other types.

Pozidriv Head Screws: Enhanced Grip for Precision Work

Pozidriv head screws, an evolution of the Phillips design, feature additional lines at 45 degrees to the main cross. This configuration significantly increases the contact area between the screwdriver and the screw, leading to a more secure fit.

This design minimizes slipping and allows for more precise torque control, making Pozidriv screws a preferred choice in precision assembly work, especially in European markets where their usage is more prevalent.

Slotted Head Screws: The Timeless Simplicity

The slotted screw, a classic in the fastener head family, features a single straight cut across its head. This timeless design, originating from the early days of screw manufacturing, continues to be a popular choice due to its straightforward interaction with standard flathead screwdrivers.

While slotted fastener heads are more susceptible to cam-out compared to more contemporary designs, their ease of use and simplicity make them a go-to choice in applications where extreme torque is not a primary concern. Their universal appeal lies in the fact that they can be easily installed and removed with common tools.

Security Head Screws: Safeguarding Against Tampering

Security head screws are innovatively designed to prevent unauthorized removal, making them ideal for public or high-security installations. These screws come in various designs, including Torx with a pin or one-way slotted heads, requiring special tools for installation and removal. This feature is crucial for ensuring safety and security in sensitive environments, such as public facilities, electronic devices, and areas prone to vandalism.

Spanner Head Screws: The Dual-Hole Defense

Spanner head screws, also known as "snake eyes" or "pig nose" screws, feature two small, round holes on the head, requiring a specialized spanner bit for manipulation. This unique design adds an extra layer of security, making these screws a popular choice for environments where tampering or unauthorized access is a concern. Commonly found in public restrooms, transit systems, and children's playground equipment, spanner screws provide both security and safety.

Tri-Wing Head Screws: The Aerospace Favorite

Tri-Wing head screws, recognized by their triangular slotted design, are engineered for applications where a secure fit and high torque resistance are paramount. They are especially favored in the aerospace industry and electronic manufacturing due to their resistance to cam-out and the ability to withstand vibrations without loosening. The unique design also adds a level of security, as they require a specific type of screwdriver.

Allen Head Screws (or Socket Head Cap Screws)

Allen head screws, or socket cap heads, are identified by their hexagonal recess, which is compatible with an Allen key, hex key, or Allen wrench. This design allows for a much tighter fit and higher torque application, making these screws a staple in machinery and precision engineering.

Socket head cap screws are particularly favored in assembling bikes and engine parts, where a secure and tight fastening is crucial. The internal hex design also means the screw head can be lower profile, which is beneficial in applications where space is limited or a flush surface is needed.


Machine Screws

Machine screws are a distinct category of screw types. While they may share some head types with the examples mentioned earlier, machine screws are defined by their uniform threading, finer pitch than wood or sheet metal screws, and are designed to fasten metal parts together.

They're used to hold parts together in all types of machines such as electronics, engines and huge industrial manufacturing equipment. Occasionally, they're also called stove bolts. Typically, they're threaded through preexisting, tapped holes — as opposed to creating the hole as you screw them in. Still, some machine screws have tapping ability to cut and thread a hole as they're inserted.


Machine screws come in coarse thread, which means they have 24 threads per inch, and in fine thread, which means they have 32 threads per inch. Machine screws come with different types of heads.

Machine Screw Head Types

The most common types of machine screw head shapes are pan head, flat head, round head, oval head, truss head and hex head. Most of the various head types are available with either slotted or Philips screwdriver compatibility, and some come with a combination head that is compatible with both.

On the fillister and cheese head machine screws, the slot is deeper than others so you can apply more power when you drive them in. Meanwhile, tamper-resistant machine screws make it difficult for unauthorized people to get into whatever you've screwed shut.


Machine screws are different from other types of screws, such as sheet metal screws, which are threaded the whole way down and are meant to attach metal to metal. Set screws are designed especially to withstand rattling and vibrations without coming undone, and wood screws are threaded from the bottom, three-quarters of the way toward the head.

Pan Head Machine Screws: The All-Rounder

Pan head screws are recognized for their slightly rounded tops and flat bearing surfaces. Their design allows for a good balance between head height and surface area, making them suitable for a variety of applications where the head can protrude above the surface. Ideal for use in metalworking, electronics, and woodworking, these screws provide a secure hold without the need for countersinking.

Flat Head Machine Screws: Flush and Functional

Flat head machine screws are designed to sit flush with the surface they are screwed into, thanks to their tapered heads. This feature makes them ideal for applications where a smooth, finished appearance is desirable, such as in decorative hardware or cabinetry. Their countersunk heads allow for a sleek look and prevent snagging, providing both aesthetic and practical benefits.

Round Head Machine Screws: The Domed Head Solution

Round head machine screws come with a dome-shaped top, offering a distinct aesthetic. Their round profile makes them a suitable choice for projects where the screw head is meant to be visible and a more decorative look is preferred. Common in consumer electronics and furniture assembly, these screws offer a blend of functionality and style.

Oval Head Machine Screws: Elegance Meets Efficiency

Oval head machine screws feature a head that combines the characteristics of flat and round heads. The top of the head is slightly rounded, tapering down towards the base, which allows for a subtle, decorative finish when installed. These screws are often used in applications where a more refined look is desired without sacrificing the countersinking advantages of flat heads.

Truss Head Machine Screws: Broad and Low-Profile

Truss heads have a wide, low-profile head, offering a larger surface area than other screw types. This design helps distribute the pressure over a broader area, making them ideal for applications requiring a secure hold with minimal surface damage. Truss head screws are commonly used in sheet metal work, where their wide head can hold thin materials without tearing through.

Hex Head Machine Screws: Robust and Reliable

Hex heads are characterized by their hexagonal shape, designed to be driven by a wrench or socket. This design allows for high torque application, making them a go-to choice for heavy-duty mechanical applications.

They are particularly favored in construction and automotive industries, where their robust design ensures a strong, secure fastening. Hex head screws are also useful in situations where space is limited, as their external drive head does not require as much clearance as a screwdriver or Phillips head would.

This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.