Standard Flat Washers
What are standard flat washers? Standard flat washers are general-purpose round washers that distribute a fastener's load over a wider area and protect the surface under a bolt or nut. Offered in the widest range of materials, from 18-8, 304, and 316 stainless to aluminum, brass, silicon bronze, and zinc, they are the everyday washer for most fastening jobs.
Standard vs USS and SAE flat washers
Standard flat washers cover general-purpose sizing for everyday work, while USS and SAE are specific dimensional patterns. For a given bolt, a USS washer has a larger outer diameter and thicker body for heavy and structural loads, and an SAE washer has a smaller outer diameter and tighter fit for automotive and tight-clearance work, recommended with Grade 5 and Grade 8 cap screws. Choose the pattern for the bearing area and clearance you need, then choose the material for the environment, with 316 or A4 for coastal exposure and aluminum, brass, or silicon bronze for weight, conductivity, or marine needs.
Material choices for standard flat washers
- Stainless (18-8, 304, 316): corrosion resistance, with 316 for coastal use.
- Metric stainless (A2, A4): A2 comparable to 304, A4 to 316.
- Aluminum, brass, silicon bronze: light weight, conductivity, and marine resistance.
- Zinc and structural: economical plating and high-strength alloy options.
Common applications for standard flat washers
- General assembly under bolts and nuts
- Machinery, brackets, and fixtures
- Marine and coastal hardware (316, A4, bronze)
- Electrical and decorative work (brass, bronze)
For heavier or structural loads, see USS flat washers, for automotive and tight fits see SAE flat washers, and browse every option on the main flat washers category.
Standard Flat Washers FAQ
What is the difference between standard, USS, and SAE washers?
Standard is general-purpose sizing. USS has a larger outer diameter and thicker body for heavy loads, and SAE has a smaller outer diameter and tighter fit for automotive and tight-clearance use.
What materials do standard flat washers come in?
18-8, 304, and 316 stainless, metric A2 and A4, aluminum, brass, silicon bronze, zinc, and structural alloy, so you can match the washer to the environment and job.
Which material for coastal use?
Use 316 or metric A4 stainless, or silicon bronze, for coastal and saltwater exposure, since they resist pitting far better than zinc or 18-8.