US Standard Thread Length for Bolts

Bolt Diameter Standard Thread Length (in.) *
Bolts 6 inches and shorter Bolts longer than 6 inches
1/4 3/4 1
5/16 7/8 1-1/8
3/8 1 1-1/4
7/16 1-1/8 1-3/8
1/2 1-1/4 1-1/2
5/8 1-1/2 1-3/4
3/4 1-3/4 2
7/8 2 2-1/4
1 2-1/4 2-1/2
* Important note: Some bolts may vary from the standard thread length.