Screw threads

In the following 4 tables you will find the most common screw threads of the metric, English and American screw thread systems. The tightening moments are just average indicative values and must always be calculated separately for each case depending on the emerging friction coefficients (μG = coefficient of friction of the screw thread & μK = friction coefficient of the adherence surface).

Nominal diameter Indication Isometric thread English thread
Metrical English USA Rough Drilling
diam
Fine Drilling
diam
Extra fine BSW Drilling
diam
BSF Drilling
diam
BSP Drilling
diam
1 M1 0,25 0,75 0,2
1,2 M1,2 0,25 0,95 0,2
1,524 Nr.0
1,588 1/16″ 60
1,6 M1,6 0,35 1,25 0,2
1,854 Nr.1
2 M2 0,4 1,6 0,25
2,184 Nr.2
2,2 0,45 0,25
2,381 3/32″ 2,05 48
2,5 M2,5 0,45 0,35
2,515 Nr.3
2,845 Nr.4
3 M3 0,5 2,5 0,35 2,65
3,175 1/8″ Nr.5 40 2,6 2,6
3,505 Nr.6
3,969 5/32″ 32
4 M4 0,7 3,3 0,5 3,5
4,166 Nr.8
4,763 3/16″ 24 32
4,826 Nr.10
5 M5 0,8 4,2 0,5 4,5
5,486 Nr.12
5,556 7/32″ 24 28
6 M6 1 5 0,75 5,2
6,35 1/4″ 1/4″ 20 5,1 26 5,4
7 M7 1 6 0,75
7,938 5/16″ 5/16″ 18 6,5 22 6,8
8 M8 1,25 6,8 1 7
9,525 3/8″ 3/8″ 16 7,9 20 8,3
9,728 G1/8″ 28 8,8
10 M10 1,5 8,5 1,25 8,8 0,75
10,287 NPT1/8″
11,113 7/16″ 7/16″ 14 18
12 M12 1,75 10,2 1,25 10,8 1
12,7 1/2″ 1/2″ 12 10,5 16 11,2
13,157 G1/4″ 19 11,8
13,716 NPT1/4″
14 M14 2 12 1,5 12,5 1
14,288 9/16″ 9/16″ 12 16
Nominal diameter Indication Isometric thread English thread
Metrical English USA Grof Drilling
diam
Fine Drilling
diam
Extra fine BSW Drilling
diam
BSF Drilling
diam
BSP Drilling
diam
15,875 5/8″ 5/8″ 11 13,5 14 14
16 M16 2 14 1,5 14,5 1
16,662 G3/8″ 19 15,25
17,145 NPT3/8″
17,462 11/16″ 11 14
18 M18 2,5 15,5 1,5 16,5 1
19,05 3/4″ 3/4″ 10 16,5 12 17
20 M20 2,5 17,5 1,5 18,5 1
20,995 G1/2″ 14 19
21,336 NPT1/2″
22 M22 2,5 19,5 1,5 20,5 1
22,225 7/8″ 7/8″ 9 19,25 11 20
22,911 G5/8″ 14 21
24 M24 3 21 2 22 1
25,4 1″ 1″ 8 22 10 23
26,441 G3/4″ 14 24,5
26,67 NPT3/4″
27 M27 3 24 2 25 1,5
28,575 1″1/8 1″1/8 7 9
30 M30 3,5 26,5 2 1,5
30,201 G7/8″ 14 28,25
31,75 1″1/4 1″1/4 7 27,75 9 29
33 M33 3,5 29,5 2 1,5
33,249 G1″ 11 30,75
33,401 NPT1″
34,925 1″3/8 1″3/8 6 8
36 M36 4 32 3 1,5
37,897 G1″1/8 11 35,3
38,1 1″1/2 1″1/2 6 33,5 8 35
39 M39 4 35 3 1,5
41,275 1″5/8 5 8
41,91 G1″1/4 11 39,5
42 M42 4,5 37,5 3 1,5
44,323 G1″3/8 11
44,45 1″3/4 1″3/4 5 39 7 41
45 M45 4,5 40,5 3 1,5
47,625 1″7/8 4,5 7
47,803 G1″1/2 11 45,5
48 M48 5 43 3 1,5
48,001 NPT1″1/2
50,8 2″ 2″ 4,5 44,5 7 47,5
52 M52 5 47 3 2
53,75 G1″3/4 11 51,4
59,61 G2″ 11 57,2

 

Nominal diameter Indication USA thread Tightening moments in Nm
Metri-
cal
Eng USA UNC Drilling
diam
UNF Drilling
diam
8UN NPT Drilling
diam
4.6 5,6 8,8 10,9 12.9 Inox A2-A4 Tension force bolt
1 M1
1,2 M1,2
1,524 Nr.0 80
1,588 1/16″
1,6 M1,6
1,854 Nr.1 64 72
2 M2
2,184 Nr.2 56 64
2,2
2,381 3/32″
2,5 M2,5
2,515 Nr.3 48 56
2,845 Nr.4 40 48
3 M3
3,175 1/8″ Nr.5 40 44
3,505 Nr.6 32 40
3,969 5/32″
4 M4
4,166 Nr.8 32 36
4,763 3/16″
4,826 Nr.10 24 32
5 M5
5,486 Nr.12 24 28
5,556 7/32″
6 M6 4,1 5 11 15 17 8,5
6,35 1/4″ 1/4″ 20 5,1 28 5,5
7 M7
7,938 5/16″ 5/16″ 18 6,6 24 6,9
8 M8 9,8 12 26 40 41 21
9,525 3/8″ 3/8″ 16 8 24 8,5
9,728 G1/8″
10 M10 20 25 53 75 83 42
10,287 NPT1/8″ 27 8,5
11,113 7/16″ 7/16″ 14 9,4 20 9,9
12 M12 35 42 90 125 145 70 120
12,7 1/2″ 1/2″ 13 10,8 20 11,5
13,157 G1/4″
13,716 NPT1/4″ 18 11
14 M14 53 66 140 200 230 98
14,288 9/16″ 9/16″ 12 12 18 12,9
15,875 5/8″ 5/8″ 11 13,5 18 14,5
Nominal diameter Indication USA thread Tightening moments in Nm
Metri-
cal
Eng USA UNC Drilling
diam
UNF Drilling
diam
8UN NPT Drilling
diam
4.6 5,6 8,8 10,9 12.9 Inox A2-A4 Tension force bolt
15,875 5/8″ 5/8″ 11 13,5 18 14,5
16 M16 80 100 215 300 355 150 350
16,662 G3/8″
17,145 NPT3/8″ 18 14,5
17,462 11/16″
18 M18 110 138 295 410 485 160
19,05 3/4″ 3/4″ 10 16,5 16 17,5
20 M20 155 194 415 590 690 190 600
20,995 G1/2″
21,336 NPT1/2″ 14 18
22 M22 218 275 580 820 930 275 900
22,225 7/8″ 7/8″ 9 19,5 14 20,4
22,911 G5/8″
24 M24 268 333 710 1000 1200 330 1100
25,4 1″ 1″ 8 22,25 12 23,5
26,441 G3/4″
26,67 NPT3/4″ 12 14 23
27 M27 400 493 1050 1480 1800 490 1650
28,575 1″1/8 1″1/8 7 25 12 26,5 8
30 M30 530 670 1420 2090 2400 670 2200
30,201 G7/8″
31,75 1″1/4 1″1/4 7 28 12 29,5 8
33 M33 2000 2750 3400 2700
33,249 G1″
33,401 NPT1″ 11,5 29
34,925 1″3/8 1″3/8 6 31 12 32,75 8
36 M36 2600 3580 4300 3800
37,897 G1″1/8
38,1 1″1/2 1″1/2 6 34,5 12 36 8
39 M39 3400 4800 5600
41,275 1″5/8
41,91 G1″1/4
42 M42
42,16 NPT1″1/4 11,5 38
44,323 G1″3/8
44,45 1″3/4 1″3/4 5 39,5 8
45 M45
47,625 1″7/8
47,803 G1″1/2
48 M48
48,26 NPT1″1/2 11,5 44
50,8 2″ 2″ 4,5 45,25 8
52 M52
60,32 NPT2″ 11,5 56

For the dimensions outside these tables the thread dimensions for the different types could be defined with the formulas below.

ISO-screw thread:


H = 0,86603.Ph
H1 = 0,54127.Ph = 5/8.H
h3 = 0,61343.Ph = 17/24.H
R = 0,14434.Ph = 1/6.H
D = d = Thread Dimension
D2 = d2 = d – 0,64953.Ph
D1 = d — 2.H1
d3 = d — 1,22687.Ph
A3 =Image547.Image548

AS =Image547 .Image549

Whitworth-tube thread:

Ph = Image551
H = 0,960491.Ph
h = 0,640327.Ph
r = 0,137329.Ph

Rounded thread:

H4 = h3 = 0,5.Ph
z = 0,25.Ph =Image553

D4 = d + 2.ac = d + 0,1.Ph
D1 = D4 — 2.H4 = D4 — Ph
= D — 0,9.Ph
d3 = d — 2.h3 = d – Ph
d2 = D2 = d — 2.z = d — 0,5.Ph
ac = clearance =0,05.Ph
R1 = 0,23851.Ph
R2 = 0,25597.Ph
R3 = 0,22105.Ph

Acme screwthread:


D1 = d — 2.H1 = d – Ph
H1 = 0,5.Ph
H4 = H1 + ac = 0,5.Ph + ac
h3 = H1 + ac = 0,5.Ph +ac
z = 0,25.Ph = Image555
D4 = d + 2.ac
d3 = d — 2.h3
d2 = D2 = d — 2.z = d — 0,5.Ph
ac = clearance
R1 = maximum 0,5.ac
R2 = maximum ac

Saw tooth thread:


H1 = 0,75.Ph
h3 = H1 + ac =Image557
0,86777.Ph
a = 0,1.
ac = 0,11777.Ph
w = 0,26384.Ph
e = 0,26384.Ph — 0,1. Image557
= w — a
R = 0,12427.Ph
D1 = d — 2.H1 = d — 1,5.Ph
d3 = d — 2.h3
d2 = d — 0,75 Ph
D2 = d — 0,75.Ph + 3,1758.a

The following tables show the various screw items with their corresponding DIN number. For dimensions we refer to the relevant catalogues.

 

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The table below shows the possible clamp length per bolt diameter and per bolt length.

d M12 M16 M20 M22 M24 M27 M30
L Clamp length
30 6 – 10
35 11 – 15
40 16 – 20 10 – 14
45 21 – 23 15 – 19 10 – 14
50 24 – 28 20 – 24 15 – 19 14 – 18
55 29 – 33 25 – 29 20 – 24 19 – 23
60 34 – 38 30 – 34 25 – 29 24 – 28 22 – 26
65 39 – 43 35 – 39 30 – 34 29 – 33 27 – 31
70 44 – 48 40 – 44 35 – 39 34 – 38 32 – 36 28 – 32
75 49 – 53 45 – 47 40 – 44 39 – 43 37 – 41 33 – 37 29 – 33
80 54 – 58 48 – 52 45 – 49 44 – 48 42 – 46 38 – 42 34 – 38
85 59 – 63 53 – 57 50 – 54 49 – 53 47 – 51 43 – 47 39 – 43
90 64 – 68 58 – 62 55 – 57 54 – 56 52 – 53 48 – 52 44 – 48
95 69 – 73 63 – 67 58 – 62 57 – 61 54 – 58 53 – 57 49 – 53
100 68 – 72 63 – 67 62 – 66 59 – 63 58 – 60 54 – 56
105 73 – 77 68 – 72 67 – 71 64 – 68 61 – 65 57 – 61
110 78 – 82 73 – 77 72 – 76 69 – 73 66 – 70 62 – 66
115 83 – 87 78 – 82 77 – 81 74 – 78 71 – 75 67 – 71
120 88 – 92 83 – 87 82 – 86 79 – 83 76 – 80 72 – 76
125 93 – 97 88 – 92 87 – 91 84 – 88 81 – 85 77 – 81
130 98 – 102 93 – 97 92 – 96 89 – 93 86 – 90 82 – 86
135 98 – 102 97 – 101 94 – 98 91 – 95 87 – 91
140 103 – 107 102 – 106 99 – 103 96 – 100 92 – 96
145 108 – 112 107 – 111 104 – 108 101 – 105 97 – 101
150 113 – 117 112 – 116 109 – 113 106 – 110 102 – 106
155 118 – 122 117 – 121 114 – 118 111 – 115 107 – 111
160 122 – 127 119 – 123 116 – 120 112 – 116
165 128 – 131 124 – 128 121 – 125 117 – 121
170 129 – 133 126 – 130 122 – 126
175 134 – 138 131 – 135 127 – 131
180 139 – 143 136 – 140 132 – 136
185 144 – 148 141 – 145 137 – 141
190 149 – 153 146 – 150 142 – 146
195 154 – 158 151 – 155 147 – 151
200 156 – 160 152 – 156