Threads

BSW: British Standard Whitworth Metric ISO Coarse American National Pipe Straight
BSF: British Standard FIne Metric Selected Fine American National Pipe Straight (Parallel)
Spark Plug British Standard Pipe Taper
ISO Series  'RC'		 Unified National UNC UNF UNS
  British Standard  Pipe Parallel
ISO  Series'G'		  

 

WHIT: Whitworth Form
BSW:British Standard Whitworth

 

BSF:
British Standard Fine

Tap Size

Threads per Inch

Tap Form

Drill size mm

   Tap Size

Threads
 per
 inch

Drill size mm

1/16

60

WHIT

1.2

3/16

32

4.0

3/32

48

WHIT

1.9

1/4

26

5.3

1/8

40

BSW

2.55

5/16

22

6.8

5/32

32

WHIT

3.2

3/8

20

8.3

3/16

24

BSW

3.7

7/16

18

9.8

7/32

24

WHIT

4.5

1/2

16

11.2

1/4

20

BSW

5.1

9/16

16

12.8

5/16

18

OSW

6.5

5/8

14

14.0

3/8

16

BSW

7.9

3/4

12

17.0

7/16

14

BSW

9.5

7/8

 11

20.0

1/2

12

BSW

10.5

1

10

23.0

9/16

12

BSW

12.2

1 1/4

9

28.5

5/8

11

BSW

13.5

1 1/2

8

34.5

3/4

10

BSW

16.5

1 3/4

7

40.5

7/8

9

BSW

19.5

1

8

BSW

22.0

1-1/8

7

BSW

25.0

1-1/4

7

BSW

28.0

1-1/2

6

BSW

33.5

1-3/4

5

BSW

39.0

2  

4-1/2

BSW

44.5

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Metric ISO Coarse

  

Metric Selected Fine

Tap Size

Pitch mm

Drill size mm

   Tap Size

Pitch mm

Drill size mm

2.0

.40

1.65

 8.0

1.00

7.1

2.5

.45

2.1

 10.0

1.25

8.9

3.0

.50

2.55

 12.0

1.50

10.5

3.5

.60

2.95

 14.0

1.50

12.5

4.0

.70

3.4

 16.0

1.50

14.5

4.5

.75

3.8

 18.0

1.50

16.5

5.0

.80

4.3

 20.0

1.50

18.5

6.0

1.00

5.1

 22.0

1.50

20.5

7.0

1.00

6.1

 24.0

2.00

22.0

8.0

1.25

6.9

9.0

1.25

7.9

10.0

1.50

8.6

11.0

1.50

9.5

12.0

1.75

10.2

14.0

2.00

12.2

16.0

2.00

14.25

18.0

2.50

15.75

20.0

2.50

17.5

22.0

2.50

19.5

24.0

3.00

21.0

27.0

3.00

24.0

30.0

3.50

26.5

33.0

3.50

29.5

36.0

4.00

32,0

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ANPT
 American National Pipe Straight

ANPS:
American National Pipe Straight (Parallel)
Tap Size

Pipe Taper

mm

 Tap size Threads per inch Drill size mm
1/8 27 8.4 1/8 27 8.7
1/4 18 11.2 1/4 18 11.2
3/8 18 14.25 3/8 18 15.0
1/2 14 17.5
3/4 14 23.0
1 11.5 29.0
1.25 11.5 37.5
1.5 11.5 44.0
2 11.5 56.0

Spark Plug

Tap size

Pitch
mm

Drill size mm

10.0

1.0

9.0

12.0

1.25

10.5

14.0

1.25

12.5

18.9

1.5

16.5

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UNC : Unified National Coarse

   UNF: Unified National Fine   UNS: Unified National Special

Tap Size

Threads per inch

Drill Size mm

 

 Tap size Threads per inch Drill size mm   Tap size Threads per inch Drill size mm

2

56

1.85

 

2

64

1.90

  

1/8

40

2.65

3

48

2.10

 

3

56

2.15

  

5/32

32

3.3

4

40

2.35

 

4

48

2.40

  

3/16

24

3.8

5

40

2.65

 

5

44

2.7

  

 

32

4.1

6

32

2.85

 

6

40

2.95

  

7/32

24

4.6

8

32

3.5

 

8

36

3.5

  

 

32

4.9

10

24

3.9

 

10

32

4.1

  

11/16

11

15.25

12

24

4.5

 

12

28

4.7

  

11/16

16

16.0

1/4

20

5.1

 

1/4

28

5.5

  

13/16

10

18.5

5/16

18

6.6

 

5/16

24

6.9

  

13/16

16

19.0

3/8

16

8.0

 

3/8

24

8.5

  

1

14

23.5

7/16

14

9.5

 

7/16

20

10.0

        

1/2

13

10.8

 

1/2

20

11.5

  

9/16

12

12.2

 

9/16

18

12.8

  

5/8

11

13.5

 

5/8

18

14.5

  

3/4    

10

16.5

 

3/4

16

17.5

  

7/8

9

19.5

 

7/8

14

20.5

  

1

8

22.5

 

1

12

23.5

  

1-1/8 

7

25,0

 

1-1/8

12

26,5

  

1-1/4 

7

28.0

 

1-1/4

12

29.5

  

1-3/8

6

31.0

 

1-3/8

12

33.0

  

1-1/2

6

34.0

 

1-1/2

12

36.0

  

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British Standard Pipe Taper
ISO Series  'RC'

   British Standard  Pipe Parallel
ISO  Series'G'

Tap Size

TPI

Reamer Drill Size

  

Tap Size

TPI

Drill Size

1/8

28

18.0

1/8

28

8.8

1/4

19

10.8

1/4

19

11.8

3/8

19

14.25

3/8

19

15.25

1/2

14

17.5

1/2

14

19.0

3/4    

14

23.0

5/8

14

21.0

1

11

29.0

3/4

14

24.5

1 1/4

11

37.5

7/8    

14

28.5

1 1/2

11

43.5

1

11

30.5

2

11

55.0

1-1/4

11

39.5

1-1/2

11

45.5

2       

11

57.0

2-1/2

11

72.5

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