Drive Sizes for US Allen Drive Screws


Screw Diameter

Drive Size
Socket flat head screw
Socket Flat
Socket button head screw
Socket Button
Socket cap screw
Socket Cap
Socket set screw
Set Screw
#0 0.89mm (0.035") 0.89mm (0.035") 1.27mm (0.050") 0.71mm (0.028")
#1 1.27mm (0.050") 1.27mm (0.050") 1/16" 0.89mm (0.035")
#2 1.27mm (0.050") 1.27mm (0.050") 5/64" 0.89mm (0.035")
#3 1/16" 1/16" 5/64" 1.27mm (0.050")
#4 1/16" 1/16" 3/32" 1.27mm (0.050")
#5 5/64" 5/64" 3/32" 1/16"
#6 5/64" 5/64" 7/64" 1/16"
#8 3/32" 3/32" 9/64" 5/64"
#10 1/8" 1/8" 5/32" 3/32"
#12 1/8" * 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.