Standard Thread Length for US Flange Bolts

Flange Bolt Diameter
(in.)
Standard Thread Length - IFI-111
(in.)
Flange Bolts 6" and shorter Flange Bolts longer than 6"
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"
9/16" 1-3/8" 1-5/8"
5/8" 1-1/2" 1-3/4"
3/4" 1-3/4" 2"