Washers are the unsung heroes of the fastener world, silently ensuring secure and long-lasting connections. These small, flat discs are integral to a wide array of applications, from securing bolts and screws to providing critical load distribution and vibration resistance. Hence, in this article, we will discuss washers, exploring their various types of materials and the key considerations you must make when choosing the right washer for your next project. 


From understanding how washers prevent loosening and distributing load to selecting the perfect washer for specific applications, this article equips you with the knowledge to make informed decisions and ensure your connections are built to last. So, whether you’re a seasoned DIYer or just starting, this is how to unlock the secrets of washers and become a master of secure fastening!

What is a Washer?

While they might seem simple, unassuming components, washers are vital in creating strong and secure connections. Typically crafted from metal, a washer is a flat ring with a hole in the center. When fastening something together, it sits between a nut and the surface (often another piece of metal). 

However, washers don’t just prevent things from rattling loose – they offer a multitude of benefits, such as;

  • Distributing Load: Washers help spread the pressure exerted by the tightened nut over a larger area. This prevents the surface from being damaged or dented. Imagine tightening a nut directly onto a softwood board. The concentrated pressure from the nut could easily dig into the wood. A washer distributes this pressure, protecting the wood.
  • Preventing Loosening: Washers create a tighter fit between the nut and the surface, reducing the risk of connection loosening due to vibrations or movement. Think about a car experiencing bumps and jolts on the road. Despite constant movement, washers help maintain a secure connection between nuts and bolts on the chassis.
  • Protecting Surfaces: Washers act as a barrier between the nut and the surface, preventing scratches or marring of delicate finishes. For example, a washer prevents the nut from scraping or chipping the paint when attaching a decorative bracket to a painted wall.
  • Improving Grip: The washer’s surface texture can increase friction, further enhancing the tightness of the connection. This is particularly helpful for applications where vibrations or movement might occur.

Different Types of Washers.

Washers come in various types, each designed for specific purposes and applications. Understanding the different types of washers can help you choose the right one for your project. Some types of washers include;

  1. Flat Washers
A Flat washer
A Flat washer

Flat washers are the most common type of washer. They are simple, flat, and circular with a central hole. Flat washers are used to distribute the load of a fastener evenly and provide a smooth bearing surface. They come in various sizes and thicknesses to accommodate different fasteners and applications.

  1. Spring Washers.
A Spring Washer
A Spring Washer

Spring washers, also known as split lock washers, are designed to provide a preload and prevent fasteners from loosening due to vibration or thermal expansion. They have a slightly curved or twisted shape, which gives them a spring-like action,  which helps maintain tension in the assembly, ensuring the fastener remains secure.

  1. Lock Washers.
A Lock Washer
A Lock Washer

Lock washers are specifically designed to prevent fasteners from loosening. There are several types of lock washers:

  • Split Lock Washers: These have a split and are slightly twisted, creating a spring-like action that helps maintain tension and prevent loosening.
  • Tooth Lock Washers: These have teeth that bite into the surface of the material and the fastener, providing a secure grip. Tooth lock washers come in internal and external varieties, depending on the placement of the teeth.
  1. Fender Washers
Fender Washers
Fender Washers

Fender washers have a larger outer diameter compared to standard flat washers. This design allows them to spread the load over a larger area, making them ideal for use with soft or thin materials that smaller washers could damage. Fender washers are commonly used in automotive and sheet metal applications.

  1. Countersunk Washers
Countersunk Washers
Countersunk Washers

Countersunk washers are used with countersunk screws. They have a conical shape that allows the screw head to sit flush with or below the surface of the material. This provides a smooth, finished appearance and prevents the screw head from protruding.

  1. Shoulder Washers.
Shoulder Washers
Shoulder Washers

Shoulder washers have a central protruding section (shoulder) that fits into a hole. They are often used to provide electrical insulation or to reduce wear in moving parts. Shoulder washers are commonly used in electronic equipment and machinery.

  1. Sealing Washers
A Sealing Washer
A Sealing Washer

Sealing washers have a sealing element, such as a rubber or neoprene ring, attached to them. They are used to create a watertight or airtight seal around a fastener. Sealing washers are essential in plumbing, automotive, and HVAC applications where preventing leaks is critical.

Materials Used to Make a Washer.

  • Stainless steel: A popular choice for applications requiring higher corrosion resistance than regular steel. It is important for outdoor use or in environments with moisture or chemicals.
  • Brass: A strong and corrosion-resistant material, often used in applications where aesthetics are important, such as furniture or decorative hardware. Brass washers offer a polished look that can complement the overall design.
  • Aluminum: Lightweight and corrosion-resistant, aluminum washers are used in applications where weight is a concern, such as aerospace or electronics. They are also non-sparking, making them suitable for use in hazardous environments.
  • Nylon: Non-conductive and non-corrosive nylon washers are ideal for electrical applications or situations where you want to avoid damaging delicate surfaces. They are also lightweight and provide good insulation.

Washer Standards You Need to Know.

Washers come in various sizes and thicknesses, and choosing the right one for the nut and bolt you’re using is essential. Here are two key standards to consider:

  • Diameter: The diameter of the washer should match the diameter of the nut it’s paired with. This ensures proper fit and load distribution. A washer with a hole too small for the nut won’t sit flat, compromising its effectiveness. Conversely, a washer too large will leave gaps around the nut, reducing its load-bearing capacity.
  • Thickness: Washer thickness can vary depending on the application. A thicker washer provides better load distribution and may be necessary for high-stress applications. However, excessively thick washers can create clearance issues or interfere with the functionality of the assembled components. Standard washer thicknesses are typically denoted with a gauge number, with lower numbers indicating thicker washers.

For ease of selection, washers are often specified using a combination of diameter and thickness.  For example, a “1/4-20 x 1/16” washer would indicate a washer with a 1/4-inch diameter hole and a thickness of 1/16 inch, designed for use with a 1/4-20 nut and bolt.

When selecting the right washer for your project, referring to a washer size chart is always a good practice. Most hardware stores and online retailers provide these charts to help customers choose the appropriate washer size based on the nut and bolt they use.

Here are some additional factors to consider when choosing a washer:

  • Finish: Washers come in various finishes, such as plain, zinc-plated, or stainless steel. The choice of finish depends on the application and the desired level of corrosion resistance. For example, a plain steel washer suffices for indoor use in a dry environment, while a zinc-plated washer offers better protection in a humid environment.
  • Strength: Washers are rated for strength, typically indicated by a grade number. Higher-grade washers can withstand greater loads and are suitable for heavy-duty applications.
  • Temperature: For applications exposed to extreme temperatures, washers made from high-temperature resistant materials like Inconel might be necessary.

Considerations for the Right Washer?

Choosing the right washer requires considering several factors beyond just size and material. Here are some key questions to ask yourself:

  1. What type of connection are you making? Is it a permanent or temporary connection? The application will influence the type of washer needed. A lock washer or toothwasher might be preferred for added security for permanent connections.
  2. What materials are you fastening together? Are the materials delicate or prone to scratches? If so, a nylon or plastic washer might be a better choice to prevent damage.
  3. Will the connection be exposed to the elements? A corrosion-resistant washer like stainless steel is recommended if the connection is outdoors or in a humid environment.
  4. What level of vibration will the connection experience? A lock washer or toothwasher is essential for high-vibration applications to prevent loosening.
  5. Are there any space limitations? A thinner washer might be necessary to ensure proper fit if space is tight.


Washers are essential in many fastening applications, providing load distribution, vibration resistance, sealing, and electrical insulation. Understanding the different types of washers, the materials they are made from, and the standards they adhere to is crucial for selecting the right washer for your needs. 

By considering factors like load distribution, vibration resistance, material compatibility, sealing requirements, electrical insulation, and environmental conditions, you can ensure that your fasteners remain secure and your components stay protected.


What is the primary purpose of a washer?

    The primary purpose of a washer is to distribute the load of a fastener, prevent loosening, and protect surfaces from damage. Washers ensure that fasteners remain secure and components stay in place.

    What are the different types of washers?

    The different types of washers include flat washers, spring washers, lock washers, fender washers, countersunk washers, shoulder washers, and sealing washers. Each type of washer is designed for specific applications and offers unique benefits.

    What materials are washers made from?

    Washers can be made from various materials, including steel, stainless steel, brass, copper, plastic, and rubber. The choice of material depends on the application and the environmental conditions the washer will be exposed to.

    How do I choose the right washer for my application?

    Consider factors such as load distribution, vibration resistance, material compatibility, sealing requirements, electrical insulation, and environmental conditions when choosing a washer. Selecting the right washer ensures optimal performance and longevity of the fastening assembly.

    What are washer standards?

    Washer standards, such as ANSI, DIN, ISO, and BS, specify the dimensions, materials, and performance requirements for washers to ensure consistency and reliability. These standards help ensure that washers meet specific quality and safety criteria.

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