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JIS and DIN hex socket screws - A comparison

Hex socket screws are an indispensable component in the assembly and construction of machinery and equipment. They are used worldwide, with each country having its own standards for size, thread, and materials. One of the most popular standards is the Japanese Industrial Standard (JIS). In this blog post, we will take an in-depth look at hex socket screws and the Japanese JIS standard.

What are hex socket screws?

Hex socket screws are a special type of screw that has a hexagonal recess on the head. They are mainly used to fasten elements and components, such as control panels, enclosures, or tools. They are available in a variety of sizes and materials and can be used for different applications.

  • (a) - The screw ends must be chamfered in accordance with JIS B 1003. However, a rough tip may be used for M4 or smaller.
  • (b) - Incomplete thread length at the screw tip u≤2P.
  • (c) - The opening of the hexagonal hole may have a slight rounding or chamfer.
  • (d) - Applies to those for which a minimum value of ℓs is specified.
  • (e) - It may be engraved on a flat surface.
  • (f) - The corners of the top of the head shall be rounded or chamfered at the manufacturer’s discretion.
  • (g) - The corners of the head seat must be rounded or chamfered up to dw and must not have any burrs or similar defects.
  • (h) - In the case of slotting, the remaining bore must not exceed 1/3 of the length of the hexagon side (e/2).
  • (i) - Specifies the position from which dw is measured.

Using Allen screws effectively and safely

When used in combination with nuts and washers, hex socket screws can be fastened even more securely—ensuring that all components are firmly connected and that no movement or vibration can occur. The nut ensures that the screw stays firmly in place, while the washer distributes the weight evenly, preventing the material from slipping or stretching out.

When selecting nuts and washers, ensure that they match the size and material of the screw being used. This is how MISUMI ensures that everything fits together perfectly and no weak points arise.

Advantages of the Japanese JIS Standard

The Japanese Industrial Standard (JIS) is a standardization system that specifies the sizes, threads, and materials of hex socket screws. This standard is used by the Japan Industrial Standards Committee (JIC) for the manufacture and sale of screws in Japan.

The Japanese JIS standard has several advantages over other standards. For example, the sizes and threads of the screws are very precise, allowing them to be used in a wide variety of applications. In addition, the materials used to manufacture the screws are high-quality and durable.

Dimensions of hex socket cap screws (coarse thread)

Unit: mm
Thread designation d M1.6 M2 M2.5 M3 M4 M5 M6 M8
P, screw pitch 0.35 0.4 0.45 0.5 0.7 0.8 1 1.25
bb) Reference 15 16 17 18 20 22 24 28
dk Maximum c) 3 3.8 4.5 5.5 7 8.5 10 13
Maximum d) 3.14 3.98 4.68 5.68 7.22 8.72 10.22 13.27
Minimum 2.86 3.62 4.32 5.32 6.78 8.28 9.78 12.73
da Maximum 2 2.6 3.1 3.6 4.7 5.7 6.8 9.2
ds Maximum 1.6 2 2.5 3 4 5 6 8
Minimum 1.46 1.86 2.36 2.86 3.82 4.82 5.82 7.78
e e),f) Minimum 1.733 1.733 2.303 2.873 3.443 4.583 5.723 6.863
ℓf Maximum 0.34 0.51 0.51 0.51 0.6 0.6 0.68 1.02
k Maximum 1.6 2 2.5 3 4 5 6 8
Minimum 1.46 1.86 2.36 2.86 3.82 4.82 5.7 7.64
r Minimum 0.1 0.1 0.1 0.1 0.2 0.2 0.25 0.4
s f)s Designation 1.5 1.5 2 2.5 3 4 5 6
Maximum 1.58 1.58 2.08 2.58 3.08 4.095 5.14 6.14
Minimum 1.52 1.52 2.02 2.52 3.02 4.02 5.02 6.02
t Minimum 0.7 1 1.1 1.3 2 2.5 3 4
v Maximum 0.16 0.2 0.25 0.3 0.4 0.5 0.6 0.8
dw Minimum 2.72 3.48 4.18 5.07 6.53 8.03 9.38 12.33
w Minimum 0.55 0.55 0.85 1.15 1.4 1.9 2.3 3.3
b - Applies to non-shaded areas between thick stair lines (tables ℓ, ℓs and ℓℊ).
c -Applies to heads without knurling.
d - Applies to heads with knurling.
e - The minimum value of e is 1.14 times the minimum value of s.
f - For the guage test of the hexagon hole dimensions s and e, see JIS B 1016.
g - The nominal length range in general traffic is within the frame of the thick stair line. The hatched parts must be fully threaded, and the length of the incomplete threaded part at the lower end of the neck must not exceed 3P.
The values for the non-shaded positions refer to the values ℓℊ ℓs and are based on the following equations
ℓℊmax = ℓnom -b
ℓsmin = ℓℊmax -5P
Unit: mm
Thread designation d M10 M12 M14 M16 M20 M24 M30
P, screw pitch 1.5 1.75 2 2 2.5 3 3.5
b b) Reference 32 36 40 44 52 60 72
dk Maximum c) 16 18 21 24 30 36 45
Maximum d) 16.27 18.27 21.33 24.33 30.33 36.39 45.39
Minimum 15.73 17.73 20.67 20.67 29.67 35.61 44.61
da Maximum 11.2 13.7 15.7 17.7 22.4 26.4 33.4
ds Maximum 10 12 14 16 20 24 30
Minimum 9.78 11.73 13.73 15.73 19.67 23.67 29.67
e e),f) Minimum 9.149 11.429 13.716 15.996 19.437 21.734 25.154
ℓℓ Maximum 1.02 1.45 1.45 1.45 2.04 2.04 2.89
k Maximum 10 12 14 16 20 24 30
Minimum 9.64 11.57 13.57 15.57 19.48 23.48 29.48
r Minimum 0.4 0.6 0.6 0.6 0.8 0.8 1
s f) Designation 8 10 12 14 17 19 22
Maximum 8.175 10.175 12.212 14.212 17.23 19.275 22.275
Minimum 8.025 10.021 12.032 14.032 17.05 19.065 22.065
t Minimum 5 6 7 8 10 12 45427
v Maximum 1 1.2 1.4 1.6 2 2.4 3
dw Minimum 15.33 17.23 20.17 23.17 28.87 34.81 43.61
w Minimum 4 4.8 5.8 6.8 8.6 10.4 13.1
b - Applies to non-shaded areas between thick stair lines (tables ℓ, ℓs and ℓℊ).
c - Applies to heads without knurling.
d - Applies to heads with knurling.
e - The minimum value of e is 1.14 times the minimum value of s.
f - For the gauge test of the hexagon hole dimensions s and e, see JIS B 1016.
g - The nominal length range in general traffic is within the frame of the thick stair line. The hatched parts must be fully threaded, and the length of the incomplete threaded part at the lower end of the neck must not exceed 3P.
The values for the non-shaded positions refer to the values ℓℊ ℓs and are based on the following equations
ℓℊmax = ℓnom -b
ℓsmin = ℓℊmax -5P

ℓ, ℓs, and ℓg

Unit: mm
Nominal screw d M1.6 M2 M2.5 M3 M4 M5 M6 M8
ℓ g) ℓs and ℓg
ℓs ℓg ℓs ℓg ℓs ℓg ℓs ℓg ℓs ℓg ℓs ℓg ℓs ℓg ℓs ℓg
Length
(nominal)		 min. max. min. max. min. max. min. max. min. max. min. max. min. max. min. max. min. max.
2.5 2.3 2.7                                
3 2.8 3.2                                
4 3.76 4.24                                
5 4.76 5.24                                
6 5.76 6.24                                
8 7.71 8.29                                
10 9.71 10.29                                
12 11.65 12.35                                
16 15.65 16.35                                
20 19.58 20.42     2 4                        
25 24.58 25.42         5.75 8 4.5 7                
30 29.58 30.42             9.5 12 6.5 10 4 8        
35 34.5 35.5                 11.5 15 9 13 6 11    
40 39.5 40.5                 16.5 20 14 18 11 16 5.75 12
45 44.5 45.5                     19 23 16 21 10.75 17
50 49.5 50.5                     24 28 21 26 15.75 22
55 54.4 55.6                         26 31 20.75 27
60 59.4 60.6                         31 36 25.75 32
65 64.4 65.6                             30.75 37
70 69.4 70.6                             35.75 42
80 79.4 80.6                             45.75 52
90 89.3 90.7                                
100 99.3 100.7                                
Unit: mm
Nominal screw d M10 M12 M14 M16 M20 M24 M30
ℓ g) ℓs and ℓg
ℓs ℓg ℓs ℓg ℓs ℓg ℓs ℓg ℓs ℓg ℓs ℓg ℓs ℓg
Length
(nominal)		 min. max. min. max. min. max. min. max. min. max. min. max. min. max. min. max.
10 9.71 10.29                            
12 11.65 12.35                            
16 15.65 16.35                            
20 19.58 20.42                            
25 24.58 25.42                            
30 29.58 30.42                            
35 34.5 35.5                            
40 39.5 40.5                            
45 44.5 45.5 5.5 13                        
50 49.5 50.5 10.5 18                        
55 54.4 55.6 15.5 23 10.25 19                    
60 59.4 60.6 20.5 28 15.25 24 10 20                
65 64.4 65.6 25.5 33 20.25 29 15 25 11 21            
70 69.4 70.6 30.5 38 25.25 34 20 30 16 26            
80 79.4 80.6 40.5 48 35.25 44 30 40 26 36 15.5 28        
90 89.3 90.7 50.5 58 45.25 54 40 50 36 46 25.5 38 15 30    
100 99.3 100.7 60.5 68 55.25 64 50 60 46 56 35.5 48 25 40    
110 109.3 110.7     65.25 74 60 70 56 66 45.5 58 35 50 20.5 38
120 119.3 120.7     75.25 84 70 80 66 76 55.5 68 45 60 30.5 48
130 129.2 130.8         80 90 76 86 65.5 78 55 70 40.5 58
140 139.2 140.8         90 100 86 96 75.5 88 65 80 50.5 68
150 149.2 150.8             96 106 85.5 98 75 90 60.5 78
160 159.2 160.8             106 116 95.5 108 85 100 70.5 88
180 179.2 180.8                 115.5 128 105 120 90.5 108
200 199.1 200.9                 135.5 148 125 140 110.5 128

Note

  • g - The nominal length range for general use falls within the thick dashed line. The hatched sections must be fully threaded, and the length of the unthreaded section at the lower end of the neck must not exceed 3P.
    • The values for the unshaded positions refer to the values ℓg and ℓs and are based on the following equations
    • ℓgmax=ℓnom-b
    • ℓsmin=ℓgmax-5P

Dimensions of the drill holes and screw holes for hex socket screws

Hex socket screw, drill hole dimensions
Hex socket screw, drill hole dimensions
Dimensions of bore holes and screw hole for Allen screws - Unit: mm
Thread designation (d) M3 M4 M5 M6 M8 M10 M12 M14 M16 (M18) M20 (M22) M24 (M27) M30
ds 3 4 5 6 8 10 12 14 16 18 20 22 24 27 30
d’ 3.4 4.5 5.5 6.6 9 11 14 16 18 20 22 24 26 30 33
dk 5.5 7 8.5 10 13 16 18 21 24 27 30 33 36 40 45
D' 6.5 8 9.5 11 14 17.5 20 23 26 29 32 35 39 43 48
k 3 4 5 6 8 10 12 14 16 18 20 22 24 27 30
H' 2.7 3.6 4.6 5.5 7.4 9.2 11 12.8 14.5 16.5 18.5 20.5 22.5 25 28
H'' 3.3 4.4 5.4 6.5 8.6 10.8 13 15.2 17.5 19.5 21.5 23.5 25.5 29 32
d2 2.6 3.4 4.3 5.1 6.9 8.6 10.4 12.2 14.2 15.7 17.7 19.7 21.2 24.2 26.7