socket wrenches

inch sizes

For socket wrenches to fit metric bolts, go here.

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The tables below show the commonly-available sizes of socket wrench and the fasteners they fit. The 8-pt sockets fit only square heads. A 12-pt socket fits both hexagonal and square heads. Twelve-point sockets also fit 12-pt heads (which are found only in aerospace bolts).

One end of a socket has a square recess which fits the socket wrench. In consumer wrenches, the square drives are ¼″, ⅜″, ½″, and ¾″. In the 1940's, Snap-On made sockets with a 5/16″ drive. One-eighth inch drive is rare, but in some use for small machine screws. Sockets are made that are deeper than the normal socket, so that they will fit over bolts that protrude so far that the normal socket will not come down far enough to engage the nut. Some firms also make an intermediate, semi-deep socket.

The size of a socket is the width-across-flats dimension. It is marked on the socket.Usually the socket is marked in a way that indicates whether it is inch or metric (metric usually has bands of a sort of knurlin). Of course, any size that is a fraction is an inch size; fractions are not allowed in metric sizing.

Most of the sockets sold are for use with hand tools. They are not suitable for use with power drivers, but the sizing of sockets made for power drivers is the same.

American Socket Wrenches: Inch Sizes to One Inch
Size,
inches
Drive size Fits head or nut of bolt with this diameter
¼″ ⅜″ ½″ ¾″
6
pt
12
pt
6pt
d
12pt
d
6
pt
8
pt
12
pt
6pt
d
12pt
d
6
pt
8
pt
12
pt
6pt
d
12pt
d
12
pt
6pt
d
12pt
d
current fasteners  
1/8     checkmark                                
5/32 checkmark                                 #0, #1 nuts  
3/16 checkmark checkmark checkmark checkmark                           #2, #3 nuts  
7/32 checkmark checkmark checkmark checkmark                              
1/4 checkmark checkmark checkmark checkmark   checkmark                       #4 nuts  
9/32 checkmark checkmark checkmark checkmark                              
5/16 checkmark checkmark checkmark checkmark   checkmark                       #5, #6 nuts  
11/32 checkmark checkmark checkmark checkmark                           #8 nuts  
⅜″ checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark   checkmark checkmark checkmark       ¼″ square, #10 nut  
7/16″ checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark       #12 nut, ¼″ except sq.  
½ checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark   checkmark checkmark 5/16″  
9/16 checkmark checkmark checkmark checkmark checkmark   checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark   checkmark checkmark 3/8″ 5/16 hex nut
  pre-1950s
19/32                       checkmark              
5/8 checkmark       checkmark   checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark   checkmark checkmark 7/16″ bolts, sq. nuts 3/8″ hex nut
  pre-1950s
21/32                       checkmark              
11/16         checkmark   checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark   checkmark checkmark 7/16″ hex nut  
3/4         checkmark   checkmark checkmark checkmark checkmark checkmark checkmark checkmark checkmark   checkmark checkmark ½″ 7/16″ hex nut
pre-1950s
25/32                       checkmark         checkmark    
13/16         checkmark   checkmark checkmark checkmark checkmark   checkmark checkmark checkmark   checkmark checkmark 9/16″ hex bolts ½″ hex nut
pre-1950s
7/8               checkmark checkmark checkmark   checkmark checkmark checkmark checkmark checkmark checkmark 9/16″ hex nuts  
15/16                   checkmark   checkmark checkmark checkmark checkmark checkmark checkmark 5/8″  
1                   checkmark   checkmark checkmark checkmark checkmark checkmark checkmark   5/8″ hex nut
pre-1950s
1 1/16                   checkmark   checkmark checkmark checkmark checkmark checkmark checkmark    
1 1/8                   checkmark   checkmark checkmark checkmark checkmark checkmark checkmark    
1 3/16                             checkmark        
1 1/4                   checkmark   checkmark     checkmark        
1 5/16                             checkmark     5/8″  
1 3/8                             checkmark        
1 7/16                             checkmark        
                            checkmark     1  
1 5/8                             checkmark        
1 11/16                             checkmark        
                            checkmark        
1 13/16                             checkmark        
1 7/8                             checkmark        
2                             checkmark        
2 1/8                             checkmark        
                            checkmark        

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