Fender Washer
Washers · large OD washer · penny washer · body washer
Definition: A fender washer is a flat washer with an extra-large outside diameter, made to spread load over thin or soft material and cover oversized holes.
Anatomy & Schematic
■ Body■ Hole
Governing standards: Manufacturer specified (no universal standard)
Common Sizes
| Inch | Metric | Head width | Head height |
|---|---|---|---|
| 1/4 | M6 | 1 OD | 0.05 |
| 5/16 | M8 | 1-1/4 OD | 0.06 |
| 3/8 | M10 | 1-1/2 OD | 0.06 |
Representative sizes. Full dimensional data lives in the standards listed below.
Grades & Strength
| Grade | Material | Tensile (psi) | Marking |
|---|---|---|---|
| Zinc steel | carbon steel, zinc-plated | — | None |
| Stainless | 304 stainless | — | None |
Materials
- Zinc-plated steel
- Stainless steel
- Hot-dip galvanized steel
Pros & Cons
Pros
- Spreads load over a much larger area
- Covers oversized holes
- Protects thin materials from tear-out
Cons
- Thin — not a structural washer
- Flexes under very high clamp loads
- Bulky appearance
Typical Uses
- Sheet metal and fiberglass
- Automotive fenders and panels
- Oversized or slotted holes
- Deck boards and thin wood
Alternatives & Related
- Flat Washer — Standard OD for general use
- Structural Washer — Thick, heavy washers for structural bolts
Where to Buy
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FAQ
Fender washer vs flat washer?
A fender washer is simply a flat washer with a much larger outside diameter. Use it on thin or soft material where a normal washer would pull through.
When should I use a fender washer?
On sheet metal, fiberglass, plastic, or oversized holes — anywhere you need to spread the clamp load over a bigger area.