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.