O Ring Size Charts are defined as the charts that show the globally recognized standard sizes of O rings that are accepted by the industries. As O rings are used in large number of applications and these are used in almost every industrial equipment, a common practice of standardizing the O ring sizes are much needed. These O rings size charts helps in describing the industry standard sizes for o rings.

O rings are very commonly used seals and find its requirements in large variety of industrial applications. Because of this, there exist unlimited number of various sizes of O rings and thus, there is a need to standardize the sizes of O rings. This is done by developing size standards for O rings as per the O Ring Size Charts.

There are various O rings size charts used in various countries that have become a common standard reference within industrial applications.

• AS568 – This size chart is a standard sizing chart used in United States published by S.A.E. (Society of Automotive Engineers) and defines “Inch sizes” of O rings.
• BS 1806 – This size chart is a standard sizing chart as per British Standard Institution and contains all imperial standard sizes. It consists of all those sizes which are present in AS568 metric size chart plus several more sizes which are between AS568 metric sizes.
• ISO 3601 – This is the size chart specification by International Organization for Standardization and consist Classes A & B type size O rings.
• BS 4518 – This is again standard sizing chart as per British Standard Institution and provide O ring sizes as per British Standard metric sizes commonly used by industries in European region.
• SMS 1586 – This size chart is a standard sizing chart as per Swedish Mechanical Standards where O rings are identified by internal diameters and Cross sections.
• DIN 3771 – This size chart is a standard sizing chart as per German Standards Institute where O rings are identified by internal diameters and Cross sections.
• NFT 47-501 – This standard size chart is similar to ISO 3601-1 and represents French Standard Institute.
• JIS B 2401 – This size chart is a standard sizing chart as per Japanese Industrial Standards and commonly called as Japanese Metrics.
• ISO 6149 – The O rings falling under this standard size charts are designed to be used only for Metric Tube Fittings. It has 13 different sizes and provides metric thread size for each o ring sizes.
• Generic Metric O ring sizing chart – It includes generalized or very common o ring sizes that may or may not matches any international standard sizes.