Wiha Tools USA - selling Wiha made hand tools in the United States since 1985
Socket Head Cap Screw Key Size Chart
Screw
Size
Decimal 
Equiv. 
(Inches)
Hex
Key Size
(Inches)
Head
Height
(Inches)
Head
Diameter
(Inches)
No. 0
0.060 0.050 0.060 0.096
No. 1
0.073 1/16 0.073 0.118
No. 2
0.086 5/64 0.086 0.140
No. 3
0.099 5/64 0.099 0.161
No. 4
0.112 3/32 0.112 0.183
No. 5
0.125 3/32 0.125 0.205
No. 6
0.138 7/64 0.138 0.226
No.  8
0.164 9/64 0.164 0.270
No. 10
0.190 5/32 0.190 0.312
No. 12
0.216 5/32 0.216 ???
1/4" 0.250 3/16 1/4 3/8
5/16" 0.313 1/4 5/16 15/32
3/8" 0.375 5/16 3/8 9/16
7/16" 0.438 3/8 7/16 21/32
1/2" 0.500 3/8 1/2 3/4
5/8" 0.625 1/2 5/8 15/16
3/4" 0.750 5/8 3/4 1 1/8
7/8" 0.875 3/4 7/8 1 5/16
1" 1.000 3/4 1 1 1/2
1 1/8" 1.125 7/8 1 1/8 1 11/16
Socket Head Cap Screw Key Size Chart
DIN 912 - 1983  ISO / 4762 - 1989
Screw
Size
Hex
Key Size
MM
Head
Height
MM
Head
Diameter
MM
M 1.6
1.5 1.7 3
M 2
1.5 1.5 3.5
M 2.5
2.0 2.0 4.5
M 3
2.5 2.5 5.5
M 4
3.0 3.0 7
M 5
4.0 4.0 8.5
M 6
5.0 5.0 10
M 8
6.0 6.0 13
M 10
8.0 8.0 16
M 12
10 10 18

M 14

12 12 21
M 16 14 14 24
M 18 14 18 27
M 20 17 20 30
M 22 17 122 33
M 24 19 24 36
M27 19 27 40
M 30 22 30 45
M 33 24 33 50
M 36 27 36 54