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Technical Info

At Birmingham Fastener, we aim to provide you with the knowledge and tools for your project. Our constantly expanding Fastener Learning Hub is full of information and insights for a variety of industries. View bolt length charts, read product comparisons, and find answers to your questions about fasteners.

Bolt Length Estimation Table for F3125 Grade A325 and A490 Bolts

This table can be used as a guide for bolt length estimation for our structural bolts. Add the length below to grip to determine bolt length required. If beveled washers are used, add an additional 5/16 inch to the no washer column for each bevel washer. If you have any questions, please contact our sales team.
Nominal Bolt Diameter No Washer One Washer Two Washers
1/2 11/16 55/64 1 3/64
5/8 7/8 1 1/32 1 3/16
3/4 1 1 5/32 1 5/16
7/8 1 1/8 1 9/32 1 7/16
1 1 1/4 1 13/32 1 9/16
1 1/8 1 1/2 1 21/32 1 13/16
1 1/4 1 5/8 1 25/32 1 15/16
1 3/8 1 3/4 1 29/32 2 1/16
1 1/2 1 7/8 2 1/32 2 3/16