5/16 Washer Dimensions & Size

5/16″ washers are commonly used with 5/16-inch bolts and nuts or screws in general construction, automotive assemblies, home improvement projects, and light-to-medium industrial applications. They are designed to distribute load, protect surfaces, and improve fastening stability. Under the USS standard, a 5/16″ plain washer typically has nominal inner diameter of 3/8″ and a nominal outer diameter of 7/8″. While under the SAE standard, it has a nominal inner diameter of 11/32″ and a nominal outer diameter of 11/16″. All dimensions shown are based on USS and SAE standards.

Disclaimer: Washer dimensions and tolerances may vary by standard, manufacturer, material, or finish. Always confirm critical dimensions using the official product datasheet before installation.

Washer Diagram Anatomy
USS Standard
Dimensions Nominal Size (in) Actual Size (in)
Min Max
Inner Diameter 3/8 0.370 0.370
Outer Diameter 7/8 0.390 0.390
Thickness Not specified 0.064 0.104
SAE Standard
Dimensions Nominal Size (in) Actual Size (in)
Min Max
Inner Diameter 11/32 0.339 0.359
Outer Diameter 11/16 0.681 0.703
Thickness Not specified 0.051 0.080
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Frequently Asked Questions

What is the difference between USS and SAE washer standards?

USS (United States Standard) washers generally have a larger outer diameter and thicker profile, making them suitable for structural and general-purpose applications. While SAE (Society of Automotive Engineers) washers are typically smaller and thinner, designed for more compact and tighter fit assemblies.

What size is a 5/16″ washer?

The size of a 5/16″ washer depends on the standard. Under the USS standard, it typically has a nominal inner diameter of 3/8″ and a nominal outer diameter of 7/8″. Under the SAE standard, it usually has a nominal inner diameter of 11/32″ and a nominal outer diameter of 11/16″.

What is the inner diameter of a 5/16″ washer?

The inner diameter is larger than the bolt size to allow clearance. It is typically 3/8″ for USS washers and 11/32″ for SAE washers.

What is the outer diameter of a 5/16″ washer?

The outer diameter varies by standard, with 7/8″ for USS washers and 11/16″ for SAE washers.

How thick is a 5/16″ washer?

Washer thickness varies by standard and manufacturer; however, under USS standard 5/16″ washers typically range from 0.064 to 0.104 inch in thickness. while under the SAE standart usually have a range from 0.051 to 0.080 inch in thickness