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Hex Key Chart

 
Hex Keys - Long and Short Arm   Applicable Specifications: ASME B18.3. Hardness: RC 45-53.
Nominal 
Key or
Bit and
Socket
Size
Hex Width
Across
the Flats
Hex Width 
Across
the Corners
Length of 
Short
Arm
Length of 
Long Arm
Radius
of
Bend
Max. Min. Max. Min. Max. Min. Short
Series
Long
Series
Max. Min. Max. Min. Min.
.... 0.028 0.0280 0.0275 0.0314 0.0300 0.312 0.125 1.312 1.125 2.688 2.500 0.062
.... 0.035 0.0350 0.0345 0.0393 0.0378 0.438 0.250 1.312 1.125 2.766 2.578 0.062
.... 0.050 0.0500 0.0490 0.0560 0.0540 0.625 0.438 1.750 1.562 2.938 2.750 0.062
1/16 0.062 0.0625 0.0615 0.0701 0.0680 0.656 0.469 1.844 1.656 3.094 2.906 0.062
5/64 0.078 0.0781 0.0771 0.0880 0.0859 0.703 0.516 1.969 1.781 3.281 3.094 0.078
3/32 0.094 0.0937 0.0927 0.1058 0.1035 0.750 0.562 2.094 1.906 3.469 3.281 0.094
7/64 0.109 0.1094 0.1079 0.1238 0.1210 0.797 0.609 2.219 2.031 3.656 3.469 0.109
1/8 0.125 0.1250 0.1235 0.1418 0.1390 0.844 0.656 2.344 2.156 3.844 3.656 0.125
9/64 0.141 0.1406 0.1391 0.1593 0.1566 0.891 0.703 2.469 2.281 4.031 3.844 0.141
5/32 0.156 0.1562 0.1547 0.1774 0.1745 0.938 0.750 2.594 2.406 4.219 4.031 0.156
3/16 0.188 0.1875 0.1860 0.2135 0.2105 1.031 0.844 2.844 2.656 4.594 4.406 0.188
7/32 0.219 0.2187 0.2172 0.2490 0.2460 1.125 0.938 3.094 2.906 4.969 4.781 0.219
1/4 0.250 0.2500 0.2485 0.2845 0.2815 1.219 1.031 3.344 3.156 5.344 5.156 0.250
5/16 0.312 0.3125 0.3110 0.3570 0.3531 1.344 1.156 3.844 3.656 6.094 5.906 0.312
3/8 0.375 0.3750 0.3735 0.4285 0.4238 1.469 1.281 4.344 4.156 6.844 6.656 0.375
7/16 0.438 0.4375 0.4355 0.5005 0.4944 1.594 1.406 4.844 4.656 7.594 7.406 0.438
1/2 0.500 0.5000 0.4975 0.5715 0.5650 1.719 1.531 5.344 5.156 8.344 8.156 0.500
9/16 0.562 0.5625 0.5600 0.6420 0.6356 1.844 1.656 5.844 5.656 9.094 8.906 0.562
5/8 0.625 0.6250 0.6225 0.7146 0.7080 1.969 1.781 6.344 6.156 9.844 9.656 0.625
3/4 0.750 0.7500 0.7470 0.8580 0.8512 2.219 2.031 7.344 7.156 11.344 11.156 0.750
7/8 0.875 0.8750 0.8720 1.0020 0.9931 2.469 2.281 8.344 8.156 12.844 12.656 0.875
1 1.000 1.0000 0.9970 1.1470 1.1350 2.719 2.531 9.344 9.156 14.344 14.156 1.000
1-1/4 1.250 1.250 1.243 1.4437 1.4250 3.250 2.750 11.500 11.000 16 14.500 1.000
1-5/16 1.312 1.312 1.310 1.515 1.500 x x x x 17 16.5 1.000
1-3/8 1.375 1.375 1.373 1.588 1.540 x x x x 18 17.6 2
1-7/16 1.437 1.437 1.435 1.660 1.620 x x x x 19 18.5 2
1-1/2 1.500 1.500 1.4930 1.7325 1.7225 3.750 3.250 13.500 13.00 21 20.5 2
1-9/16 1.562 1.562 1.560 1.804 1.790 x x x x 22 21.5 2
1-5/8 1.625 1.625 1.622 1.877 1.860 x x x x 23 22.5 3
1-3/4 1.750 1.750 1.747 2.021 2 x x x x 24 23.5 3
1-7/8 1.875 1.875 1.872 2.166 2.140 x x x x 24 23.5 3
2 2 2 1.997 2.310 2.290 x x x x 25 24 3

  Applicable Specifications: ASME B18.3. Hardness: RC 45-53.

 
         

Screw Size

Allen Key Size, s

Length(inches)

Length(mm)

Short Length

M3

2.5

2.20

56

18

M4

3

2.48

63

20

M5

4

2.76

70

25

M6

5

3.15

80

28

M8

6

3.54

90

32

M10

8

3.94

100

36

M12

10

4.41

112

40

M14

12

4.92

125

45

M16

14

5.51

140

56

M18

14

5.51

140

56

M20

17

6.30

160

63

M22

17

6.30

160

63

M24

19

7.09

180

70






















Socket Head Cap Screw Specs

Allen Key (Also known as Hex Key, Hexagon Key, Socket Key, LN Key), sizes and its dimensions can be very handy while designing and selecting fasteners for your application. These dimensions of allen keys can be used to check the accessibility of your bolts were space is limited. For example for an M8 socket head cap screw we need at least 32+8(head size) = 40mm clearance above the screw for easy accessibility. Refer the following table for metric allen key sizes and dimensions for corresponding socket head cap screw based on  ISO 4762/DIN 912 standards.
Hex Wrenches Hardness of RC 48-54.