1-1/4 Washer Dimensions & Size

1-1/4″ washers are commonly used with 1-1/4-inch bolts and nuts in heavy-duty construction, structural steel connections, industrial machinery, and large-scale infrastructure projects. They are designed to distribute load, protect bearing surfaces, and maintain fastening stability under high clamping forces. Under the USS standard, a 1-1/4″ plain washer typically has a nominal inner diameter of 1-3/8” and a nominal outer diameter of 3”. While under the SAE standard, it has a nominal inner diameter of 1-5/16” and a nominal outer diameter of 2-1/2”. Washer thickness varies by standard, with USS washers typically ranging from 0.136 to 0.196 inch and SAE washers typically ranging from 0.136 to 0.192 inch. 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 1-3/8 1.368 1.405
Outer Diameter 3 2.993 3.030
Thickness Not specified 0.136 0.192
SAE Standard
Dimensions Nominal Size (in) Actual Size (in)
Min Max
Inner Diameter 1-5/16 1.368 1.405
Outer Diameter 2-1/2 2.493 2.530
Thickness Not specified 0.136 0.192
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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 heavy-duty applications. While SAE (Society of Automotive Engineers) washers are typically smaller and thinner, designed for more compact assemblies with limited space.

What size is a 1-1/4″ washer?

The size of a 1-1/4″ washer depends on the standard. Under the USS standard, it typically has a nominal inner diameter of 1-3/8″ and a nominal outer diameter of 3″. Under the SAE standard, it usually has a nominal inner diameter of 1-5/16″ and a nominal outer diameter of 2-1/2″.

What is the inner diameter of a 1-1/4″ washer?

The inner diameter is slightly larger than the bolt size to provide proper clearance. It is typically 1-3/8″ for USS washers and 1-5/16″ for SAE washers.

What is the outer diameter of a 1-1/4″ washer?

The outer diameter varies by standard, with 3″ for USS washers and 2-1/2″ for SAE washers.

How thick is a 1-1/4″ washer?

Washer thickness depends on the standard and manufacturer. USS 1-1/4″ washers typically range from 0.136 to 0.196 inch, while SAE 1-1/4″ washers typically range from 0.136 to 0.192 inch.