O-Ring Size Chart


An o-ring size chart  is one of the most common types of seals in the world. Due to this popularity and the vast array of applications in which o-rings are used, there is a virtually unlimited number of possible sizes of an o-ring. Thus, the need for size standards which cover the most common sizes used across various industries and geographic regions. Over the years, many government and engineering organizations have produced a multitude of O-Ring standards. Here we present a brief overview of what we believe to be the most often used/referenced standards by our customers in the United States and around the world.


The standard sizes are defined by Aerospace Standard AS568B, Aerospace Size Standard for O-Rings. That document, published by the Society of Automotive Engineers (SAE), lists the sizes of O-Rings in six series or groups in both inches and millimetres. The first five series are based on cross-sectional diameter. The sixth series includes 20 sizes for boss seals. The standard sizes are also used for most military specifications. Cross-sectional diameters range from 0.040 to 0.275 inch. Inside diameters range from 0.029 to 25.940 inches.


O-Ring Sizes are typically available in standard sizes per industry standards. These include:

Standard metric sizes for O-Rings are defined by International Standard ISO 3601-1:2002: Fluid power systems O-Rings Part 1: Inside diameters, cross-sections, tolerances and size identification code. That standard groups metric sizes into two series, G and A. The G series is used for general purpose applications and includes a wide range of inside diameters. The A series is used for aerospace applications where tighter tolerances are recommended.