British Pipe Thread ( Whitworth Form) -- Parallel (BSPP/BSPF)

Thread
Designation

Nominal
Size

Thread
Form
Type

Major
Diameter
mm
d=D

Pitch
mm
p

Threads
per
inch

Pitch
Diameter
mm
d2=D2

Minor
Diameter
Male Thd.
d3

Thread
Height
H1

Tap
Drill
Diameter
mm

G1/8

1/8"

BSPP

9.728

0.907

28

9.147

8.566

0.581

8.70

G1/4

1/4"

BSPP

13.157

1.337

19

12.301

11.445

0.856

11.60

G3/8

3/8"

BSPP

16.662

1.337

19

15.806

14.950

0.856

15.00

G1/2

1/2"

BSPP

20.955

1.814

14

19.793

18.631

1.162

19.00

G5/8

5/8"

BSPP

22.911

1.814

14

21.749

20.587

1.162

20.75

G3/4

3/4"

BSPP

26.441

1.814

14

25.279

24.117

1.162

24.50

G7/8

7/8"

BSPP

30.201

1.814

14

29.039

27.877

1.162

28.00

G1

1"

BSPP

33.249

2.309

11

31.770

30.291

1.479

30.50

G1-1/8

1-1/8"

BSPP

37.897

2.309

11

36.418

34.939

1.479

35.00

G1-1/4

1-1/4"

BSPP

41.910

2.309

11

40.431

38.952

1.479

39.50

G1-3/8

1-3/8"

BSPP

44.323

2.309

11

42.844

41.365

1.479

41.50

G1-1/2

1-1/2"

BSPP

47.803

2.309

11

46.324

44.845

1.479

45.00

G1-3/4

1-3/4"

BSPP

53.746

2.309

11

52.267

50.788

1.479

51.00

G2

2"

BSPP

59.614

2.309

11

58.135

56.656

1.479

57.00

G2-1/4

2-1/4"

BSPP

65.71

2.309

11

64.231

62.752

1.479

63.00

G2-1/2

2-1/2"

BSPP

75.184

2.309

11

73.705

72.226

1.479

72.50

G2-3/4

2-3/4"

BSPP

81.534

2.309

11

80.055

78.576

1.479

79.00

3

3"

BSPP

87.884

2.309

11

86.405

84.926

1.479

85.50

G3-1/4

3-1/4"

BSPP

93.98

2.309

11

92.501

91.022

1.479

91.00

G3-1/2

3-1/2"

BSPP

100.33

2.309

11

98.351

97.372

1.479

97.75

G3-3/4

3-3/4"

BSPP

106.68

2.309

11

105.201

103.722

1.479

104.00

G4

4"

BSPP

113.03

2.309

11

111.55

110.072

1.479

110.50

G4-1/2

4-1/2"

BSPP

125.73

2.309

11

124.251

122.772

1.479

123.00

G5

5"

BSPP

138.43

2.309

11

136.951

135.472

1.479

136.00

G5-1/2

5-1/2"

BSPP

151.13

2.309

11

149.651

148.172

1.479

148.50

G6

6"

BSPP

163.83

2.309

11

162.351

160.872

1.479

161.50