Standard Sizes for Bolts

Updated April 17, 2017

The establishment of regular sizes of bolts for commercial purposes are governed by three standards organisations. These are the American Society for Testing and Materials (ASTM), Society of Automotive Engineers (SAE) the International Standards Organization (ISO). Together these organisations establish and offer manufacturers guidance for any commercial outlet that fabricates, distributes, sells or applies these fasteners worldwide. Regardless of the standard, all bolts are indexed by identification, grade mark, specification, fastener description, material and nominal size range based on either Imperial inches, or the EU-based metric system.

Standard ASTM Bolt Sizes

ASTM bolts are indexed across a long list of fasteners. These range from the ASTM A490 high-strength structural bolt used as a high-strength fastener, ranging in diameter from 1/2 to 1 1/2 inches to the ASTM A354 Grade BD bolt, which offers an alloy steel, quenched and tempered product used for manufacturing purposes at diameters between 1/4to 1 1/2 inches to the ASTM A307, which is used as a large-diameter product for studs offering sizes ranging from 1/4 or 3/4 inches up to 1 1/2 inches.

Standard SAE Bolt Sizes

The Society of Automotive Engineers offer standards guidance not only for car manufacturers, but for commercial uses as well. In this case, the organisation indexes bolts based on types and grades, including SAE J429 grade 8 bolts, screws and studs, all made of medium carbon alloy steel, in diameters between 1/4 to 1 1/2 inches, the grade 5 bolt with larger diameters offering 1/4 to 1 1/2 inches and the grade 1, again made of carbon alloy, but offering larger diameters between 3/4 to 1 1/2 inches.

Standard ISO Bolt Sizes

The ISO offers a shorter index of bolts than the other standards organisations. In this case the index ranges from the R898 Class 10.9, made of alloy steel, in a diameter of 1 1/2 inches to the ISO ISO R898 Class 4.6, made of medium carbon steel, at a diameter of 1 1/2 inches.

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About the Author

Since 1984, Rick Carlton has authored more than 450 articles on the principles, application, analysis and deployment of interoperable enterprise technologies. Additionally, he has written more than 150 feature articles on aviation, auto and motorsports topics including work for The Auto Channel, "Automobile," "Flight Training" and "On-Track" magazine. He holds a Bachelor of Fine Arts in music from the University of Missouri at Kansas City.