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U.S. Bolts - Head and Wrench Sizes

Hex Bolt, Lag Bolt, Square Bolt and Heavy Hex Bolt.

hex bolt

Head and wrench size U.S. bolts:

US Bolts - Head and Wrench Sizes
Bolt Diameter
(in)
Head and Wrench Size (in)
Hex Bolt
Lag Bolt
Square Bolt
Heavy Hex Bolt
#6 1/4  
#8 1/4  
#10 5/16  
#12 5/16  
1/4 7/16 or 3/8  
5/16 1/2  
3/8 9/16  
7/16 5/8  
1/2 3/4 7/8
9/16 13/16  
5/8 15/16 1 1/16
3/4 1 1/8 1 1/4
7/8 1 5/16 1 7/16
1 1 1/2 1 5/8
1 1/8 1 11/16 1 -3/4
1 1/4 1 7/8 2
1 3/8 2 1/16
1 1/2 2 1/4
  • 1 in = 25.4 mm
  • ANSI/ASME B18.2.1 Square, Hex, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex, Hex Flange, Lobed Head, and Lag Screws (Inch Series)
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