British Standard Pipe Thread Chart

Thread Angle 55 degrees

Size

Decimal

TPI

Pitch

Core Dia

Thread
Depth

Radius

Tapping
Size

MM

Letter
or
Number

1/16

0.304

28

0.03571

0.2583

0.0229

0.0049

0.2640

6.6

G

1/8

0.383

28

0.03571

0.3372

0.0229

0.0049

0.3438

8.75

11/32

1/4

0.518

19

0.05263

0.4546

0.0337

0.0072

0.4646

11.8

15/32

3/8

0.656

19

0.05263

0.5886

0.0337

0.0072

0.6004

15.25

39/64

1/2

0.825

14

0.07143

0.7336

0.0457

0.0098

0.750

19.05

3/4

5/8

0.902

14

0.07143

0.8106

0.0457

0.0098

0.8281

21.0

53/64

3/4

1.041

14

0.07143

0.9496

0.0457

0.0098

0.9646

24.5

31/32

7/8

1.189

14

0.07143

1.0976

0.0457

0.0098

1.1122

28.25

1 - 7/64

1

1.309

11

0.09091

1.1926

0.0582

0.0125

1.2106

30.75

1 - 13/64

1 - 1/8

1.492

11

0.09091

1.3755

0.0582

0.0125

1.3935

35.4

1 - 25/64

1 - 1/4

1.650

11

0.09091

1.5336

0.0582

0.0125

1.5551

39.50

1 - 35/64

1 - 1/2

1.882

11

0.09091

1.7656

0.0582

0.0125

1.7812

45.0

1 - 25/32

1 - 3/4

2.116

11

0.09091

1.9996

0.0582

0.0125

2.0079

51.0

2"

2

2.347

11

0.09091

2.2306

0.0582

0.0125

2.250

57.0

2 - 1/4

2 - 1/4

2.587

11

0.09091

2.4706

0.0582

0.0125

2.490

63.2

2 - 1/2

2 - 1/2

2.960

11

0.09091

2.8436

0.0582

0.0125

2.863

72.7

2 - 3/4

3.210

11

0.09091

3.0936

0.0582

0.0125

3.113

79.0

3

3.460

11

0.09091

3.3436

0.0582

0.0125

3.363

85.426

3 - 1/2

3.950

11

0.09091

3.8336

0.0582

0.0125

3.853

97.872

4

4.450

11

0.09091

4.3336

0.0582

0.0125

4.353

110.572

4 - 1/2

4.950

11

0.09091

4.8334

0.0582

0.0125

4.853

123.272

5

5.450

11

0.09091

5.3336

0.0582

0.0125

5.353

135.972

5 - 1/2

5.950

11

0.09091

5.8334

0.0582

0.0125

5.853

148.672

6

6.450

11

0.09091

6.3336

0.0582

0.0125

6.353

161.372

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