AS568 Size Chart

AS568 Size Standard

The AS568 standard represents a comprehensive set of guidelines crucial for the design, quality control, manufacturing, and procurement of o-rings within the industry. Developed by the Society of Automotive Engineers (SAE), it stands as the most widely adopted o-ring sizing standard in the United States.

Understanding an o-ring’s dimensions is key to its functionality. The catalog features 394 distinct sizes, each assigned a unique “dash” number corresponding to a specific set of measurements and tolerances. This facilitates a universal benchmark that guarantees interchangeability among o-rings produced by different manufacturers.

A distinct feature of the AS568 standard is its organization into series based on cross-sectional thickness. There are six primary series: 000, 100, 200, 300, 400, and 900. Each series corresponds to a standard cross-section of 0.070 in, 0.103 in, 0.138 in, 0.210 in, and 0.275 in, respectively. The 900 series caters to varying cross-sections.

The table below specifies the dimensions and tolerances for the AS568 size identification codes (dash numbers). The table can be searched by dash #, cross-section, inside diameter, and outside diameter in inches, millimeters, or nominal values. Note that the nominal values are only in name and are often used when verbally describing the size. For an accurate measurement, refer to the actual inch or millimeter size.