O-Ring Size Charts

/O-Ring Size Charts
O-Ring Size Charts 2017-12-29T13:31:04+00:00

O-Ring Size Standards

An O-Ring is one of the most common types of seals in the world. O-Rings are used in a variety of applications in different industries around the world. Because of its popularity, there is virtually an unlimited number of possible sizes of an O-Ring. Thus, the need for size standards which cover the most common sizes used.

Over the years, many size standards have been developed for O-Rings. The table below shows what we believe to be the most often used/referenced standards by our customers in the United States and other countries.

O-Ring Size Charts

**This information is only intended as a guide to identify O-Ring sizes from the various international standards. Although we believe this information to be correct, we cannot guarantee 100% accuracy with each and every standard. Therefore, we recommend referral to the actual specifications before proceeding with design work, etc. **


AS568 is the most commonly used standard in the United States for defining “inch sizes” of o-rings.

AS568 Size Chart

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BS 1806

British Standards Institution and lists all Imperial standard sizes. It has been superseded by BS ISO 3601.

BS 1806 Size Chart

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ISO 3601

International Organization for Standardization and contains both Class A and Class B O-Rings.

ISO 3601 Size Chart

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BS 4518

Issued by the British Standards Institution, Standard BS 4518 identifies British Standard metric sizes.

BS 4518 Size Chart

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SMS 1586

Swedish Mechanical Standard (Sveriges Mekanstandardisering). O-Rings are identified by ID and C/S.

SMS 1586 Size Chart

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DIN 3771

The German Institute for Standards (Duetsches Institut für Normung). O-Ring sizes shown as ID x C/S.

DIN 3771 Size Chart

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NF T 47-501

Association Française de Normalisation (French Standards Institute). Similar to ISO 3601-1.

NF T 47-501 Size Chart

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JIS B 2401

Japanese Industrial Standard for O-Ring sizes. This standard, often referred to as “Japanese Metrics.”

JIS B 2401 Size Chart

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IS0 6149

ISO 6149 specifies O-Rings designed for use in Metric Tube Fittings. Includes 13 different sizes and calls out the metric thread size for each o-ring size.

IS0 6149 Size Chart

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Generic Metric O-Ring Sizes

Included are the most common metric sizes that may or may not match up with any of the international standard sizes.

Generic Metric O-Ring Sizes

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Metric O-Ring Size Cross Reference Table

Common international size standards and allows you to cross reference with other standards.

Metric O-Ring Size Cross Reference Table

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Size Charts in PDF Format

Need a handy reference guide? Download our entire catalog of International O-Ring Size Standards as a PDF file.

Download PDF

Download Size Charts PDF


Some of the standards referenced here do specify the acceptable tolerance ranges for the o-rings within that standard. However, With the exception of our AS568 size chart, our other size reference charts do not list tolerances, as these tend to vary between the standards issuing organizations. To view the size tolerances for the o-rings we sell, please refer to either the AS568 size chart for American Standard Sizes, or our Metric O-Ring Tolerances page for all other “metric” o-rings.

Due to icy road conditions and a power outage at our facility, Global O-Ring is closed today, Tuesday, January 16th. Dismiss