US Allen Drive Screw Size

Screw DiameterDrive Size
Socket flat head screwSocket button head screwSocket cap screwSocket set screw
Socket FlatSocket ButtonSocket CapSet Screw
#00.89mm (0.035″)0.89mm (0.035″)1.27mm (0.050″)0.71mm (0.028″)
#11.27mm (0.050″)1.27mm (0.050″)1/16″0.89mm (0.035″)
#21.27mm (0.050″)1.27mm (0.050″)5/64″0.89mm (0.035″)
#31/16″1/16″5/64″1.27mm (0.050″)
#41/16″1/16″3/32″1.27mm (0.050″)
#55/64″5/64″3/32″1/16″
#65/64″5/64″7/64″1/16″
#83/32″3/32″9/64″5/64″
#101/8″1/8″5/32″3/32″
#121/8″*5/32″3/32″
1/4″5/32″5/32″3/16″1/8″
5/16″3/16″3/16″1/4″5/32″
3/8″7/32″7/32″5/16″3/16″
7/16″1/4″1/4″3/8″7/32″
1/2″5/16″5/16″3/8″1/4″
9/16″**7/16″1/4″
5/8″3/8″3/8″1/2″5/16″
3/4″1/2″7/16″5/8″3/8″
7/8″9/16″3/4″1/2″
1″5/8″3/4″9/16″
1-1/8″3/4″7/8″
1-1/4″7/8″7/8″
1-3/8″7/8″1″
1-1/2″1″1″
* This product is not manufactured, or does not have a standardized drive size.