Distinction
Name
Diametric pitch
Class

Class 1

Class 2

Class 3

Coarseness of the thread

M3
0.5
2.66-2.64
2.63-2.60
-
3.5
0.6
3.10-3.08
3.06-3.03
3.05-3.00
4
0.7
3.54-3.51
3.49-3.45
-
4.5
0.75
4.01-3.98
3.96-3.92
3.94-3.88
5
0.8
4.47-4.44
4.43-4.38
4.40-4.33
6
1
5.34-5.31
5.30-5.25
5.28-5.21
7
1
6.34-6.31
6.30-6.25
6.28-6.21
8
1.25
7.18-7.14
7.12-7.07
7.10-7.03
9
1.25

8.18-8.14

8.12-8.07
8.10-8.03
10
1.5
9.03-8.99
8.97-8.91
8.94-8.86
11
1.5
10.02-9.98
9.97-9.91
9.94-8.86
12
1.75
10.86-10.82
10.79-10.73
10.77-10.69
14
2
12.70-12.65
12.63-12.56
12.61-12.52
16
2
14.70-14.65
14.63-14.56
14.61-14.52
18
2.5
16.38-16.33
16.31-16.23
16.28-16.17
20
2.5
18.38-18.33
18.31-18.23
18.28-18.17
22
2.5
20.38-20.33
20.31-20.23
20.28-20.17
24
3
22.07-22.01
21.98-21.90
21.96-21.85
27
3
25.06-25.00
24.98-24.89
24.95-24.84
30
3.5
27.75-27.68
27.66-27.56
27.63-27.50
33
3.5
30.74-30.68
30.65-30.56
30.62-30.50
36
4
33.43-33.37
33.33-33.23
33.29-33.16
39
4
36.43-36.36
36.32-36.22
36.27-36.11
42
4.5
39.11-39.04
39.01-38.90
38.97-38.82
45
4.5
42.11-42.04
42.00-41.90
41.96-41.82
48
5
44.75-44.60
44.68-44.45
44.68-44.37

Distinction
External diameter
Thread pitch
Class 1
Class 2
Class 3

Dainty of the thread

4
0.5
3.65-3.63
3.61-3.56
3.60-3.54
4.5
0.5
4.15-4.13
4.11-4.06
4.10-4.04
5
0.5
4.64-4.63
4.61-4.56
4.60-4.545
5.5
0.5
5.15-5.13
5.11-5.06
5.10-5.04
6
0.75
5.49-5.46
5.45-5.40
5.43-5.37
7
0.75
6.49-6.46
6.45-6.40
6.43-6.37
8
0.75
7.49-7.45
7.44-7.39
7.42-7.36
8
1
7.33-6.46
7.28-7.23
7.26-7.19
9
1
8.33-8.29
8.28-8.23
8.26-8.19
10
1
9.33-9.29
9.29-9.22
9.26-9.19
10
1.25
9.17-9.13
9.11-9.06
9.09-9.02
11
1.25
10.61-10.12
10.11-10.05
10.09-10.01
12
1.25
11.15-11.13
11.12-11.07
11.08-10.98
12
1.5
11.00-10.96
10.94-10.88
10.92-10.84
13
1.5
12.00-11.96
11.94-11.88
11.92-11.84
14
1.5
13.00-12.96
12.94-12.87
12.92-12.83
15
1.5
14.00-13.95
13.94-14.87
13.92-13.83

16

1.5
15.00-14.95
14.97-14.87
14.92-14.83

Name
Class
3A
2A
1A
No 6
32
2.98-2.95
2.95-2.91
-
No 8
32
3.64-3.61
3.60-3.57
-
No 10
24
4.12-4.09
4.09-4.05
-
No 12
24
4.78-4.75
4.75-4.70
-
1/4
20
5.53-5.50
5.50-5.45
5.47-5.40
5/16
18
7.03-6.99
6.98-6.93
6.96-6.88
3/8
16
8.50-8.46
8.45-8.40
8.43-8.34
7/16
14
9.94-9.90
9.89-9.83
9.86-9.77
1/2
13

11.44-11.39

11.39-11.32
11.35-11.26
9/16
12
12.92-12.87
12.87-12.80
12.83-12.73
5/8
11
14.39-14.34
14.33-14.26
14.30-14.19
3/4
10
17.41-17.35
17.34-17.27
17.31-17.20
7/8
9
20.40-20.34
20.34-20.26
20.30-20.17
1
8
23.35-23.33
23.28-23.20
23.24-23.11
11/8
7
26.24-26.17
26.16-26.07
26.12-25.98
11/4
7
29.41-29.34
29.33-29.24
29.28-29.14
13/8
6
32.20-32.13
32.12-32.02
32.07-31.91
11/2
6
35.53-35.20
35.29-35.08
35.29-34.98
13/4
5
41.15-40.98
41.08-40.85
41.08-40.74
2
4 1/2
47.13-46.95
47.06-46.82
47.16-47.00

Name

Class
3A
2A
1A
U No 6
40
3.08-3.06
3.05-3.02
-
No 8
36
3.69-3.67
3.66-3.63
-
No 10
32
4.29-4.26
4.26-4.22
-
No 12
28
4.88-4.85
4.84-4.80
-
1/4
28
5.75-5.72
5.72-5.68
5.70-5.63
5/16
24
7.24-7.21
7.20-7.16
7.18-7.11
3/8
24
8.83-8.79
8.79-8.74
8.76-8.69
7/16
20
10.28-10.24
10.23-10.18
10.21-10.13
1/2
20
11.86-11.82
11.82-11.76
11.79-11.71
9/16
18
13.36-13.32
13.31-13.25
13.28-13.19
5/8
18
14.94-14.90
14.89-14.83
14.86-14.77
3/4
16
18.00-17.96
17.95-17.89
17.92-17.82
7/8
14
21.03-20.98
20.98-20.91
20.94-20.84
1
12
24.01-23.96
23.95-23.87
23.91-23.80
11/8
12
27.19-27.13
27.12-27.05
27.08-26.97
11/4
12
30.36-30.30
30.29-30.21
30.25-30.14
13/8
12
33.53-33.47
33.46-33.38
33.42-30.30
11/2
12
36.70-36.64
36.63-36.55
36.59-36.47

Class
Class 2
Class 3
Class 4
W 3/16-24
4.08-4.05
4.06-4.02
4.04-3.97
1/4-20
5.51-5.46
5.49-5.42
5.47-5.38
5/16-18
7.01-6.95
6.99-6.91
6.97-6.87
3/8-16
8.48-8.41
8.46-8.37
8.44-8.33
7/16-14
9.92-9.85
9.90-9.81
9.87-9.76
1/2-12
11.31-11.24
11.29-11.19
11.27-11.15
9/16-12
12.89-12.82
12.87-12.77
12.85-12.73
5/8-11
14.36-14.29
14.34-14.24
14.31-14.18
3/4-10
17.38-17.30
17.36-17.25

17.33-17.19

7/8-9
20.38-20.29
20.34-20.23
20.32-20.18
1-8
23.32-23.23
23.29-23.17
23.26-23.11

Name
number of thread
Class 1
Class 2
Class 3
SM 1/8
40
2.748-2.718
2.735-2.688
2.713-2.648
1/8
44
2.782-2.752
2.769-2.722
2.747-2.682
9/64
40
3.143-3.113
3.128-3.083
3.108-3.043
11/64
40
3.785-3.845
3.855-3.805
3.840-3.775
3/16
32
4.220-4.185
4.205-4.155
4.190-4.125
3/16
28
4.158-4.983
4.143-4.093
4.128-4.063
7/32
32
5.018-4.983
5.003-4.955
4.983-4.913
15/64
28
5.345-5.310
5.325-5.570

5.310-5.240

1/4
40
5.910-5.875
5.890-5.735
5.870-5.795
1/4
28
5.736-5.696
5.721-5.366
5.701-5.626
9/32
28
6.508-6.448
6.508-6.648
6.493-6.418
11/32
28
8.121-8.702
8.902-8.432
8.072-7.992
3/8
28
8.905-8.865
8.880-8.015
8.865-8.785
7/16
28
10.486-10.401
10.466-10.401
10.441-10.350
7/16
16
10.062-10.017
10.819-11.749
10.012-9.917
1/2
20
11.844-11.799
11.819-11.749
11.794-11.699
9/16
20
13.425-13.375
13.400-13.425

13.380-13.285


Name
PF
PS
PT
Class A
Class B

Position for
baseline diameter

Diameter for material used
1/8-28
9.10-9.05
9.05-8.94
9.00-8.92
3.97
9.16-9.10
1/4-19
12.25-12.19
12.19-12.07
12.11-12.01
6.01
12.32-12.23
3/8-19
15.76-15.69
15.69-15.57
15.61-15.51
6.35
15.82-15.73
1/2-14
19.74-19.67
19.67-19.53
19.55-19.43
8.16
19.81-19.70
3/4-14
25.22-25.12
25.15-25.01
25.03-24.90
9.53
25.29-25.18
1-11
21.7-31.61
31.61-31.43
31.47-31.34
10.39
31.79-31.64

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