US Flange Bolt Head/Wrench Size

Flange Bolt
Diameter
Head/Wrench Size*
Hex Flange Bolt (IFI-111)
and
Hex Flange Lag
1/4" 3/8"
5/16" 1/2"
3/8" 9/16"
7/16" 5/8"
1/2" 3/4"
9/16" 13/16"
5/8" 15/16"
3/4" 1-1/8"
* This is the width across the flats.