Fender Washers

What are Fender Washers?

Fender washers are flat washers with an intentionally oversized outside diameter compared to the hole size. The wide footprint spreads clamping force, protects thin materials, and helps cover slotted or enlarged holes during assembly or repair.

What are fender washers used for?

• Protecting thin sheet, plastics, and wood from pull-through
• Bridging worn, oversized, or irregular holes
• Improving torque consistency by distributing load
• Providing light spacing when a small stand-off is needed

When should I use a fender washer?

Choose a fender washer when you need maximum surface coverage or you are repairing an enlarged opening. If space is tight and a standard footprint is sufficient, a flat washer is usually the better fit.

Fender washer vs flat washer, what’s the difference?

For the same bolt size, a fender washer has a much larger outside diameter than a flat washer. The extra bearing area spreads load and stabilizes thin or soft materials, while a flat washer prioritizes clearance and a smaller footprint.

What size fender washer do I need? (inch and metric)

• Match the nominal size to your bolt or screw, for example 1/4 in or M6
• Confirm the inner diameter clears the shank without excess play
• Select an outside diameter that fully covers the hole with margin
• Choose a thickness that resists cupping yet fits your available clearance
• Available in inch and metric ranges to pair with US and metric hardware

Materials and finishes

18-8 / 304 stainless steel

All-purpose corrosion resistance with a clean appearance for indoor and light outdoor use.

316 stainless steel

Upgraded corrosion resistance for marine, salt, or chemical exposure. Best paired with 316 fasteners.

Zinc plated steel

Economical carbon steel with a light protective coating for dry, indoor environments.

Installation tips

• Place the washer under the rotating part, either the nut or the bolt head, to protect the surface
• Tighten gradually on plastics or wood and re-check after initial compression
• Keep materials compatible, for example stainless with stainless, to reduce galvanic concerns in wet areas

Applications

• Automotive bodywork and panel mounting
• HVAC brackets, ductwork, and appliance installs
• Plastics, laminates, and composite assemblies
• Woodworking, cabinetry, fixtures, and general repairs

Compatibility and best practices

• Use 316 stainless near saltwater, 304 for general service, and zinc plated for dry interiors
• Verify outside diameter clearance so the washer does not clash with channels or flanges
• For vibration, add a locking method such as a lock washer, threadlocker, or a prevailing-torque nut