home
Thread Size - Reference Chart

To identify a thread size, measure the exterior male thread diameter or the internal female thread diameter, then match it with the corresponding measurement column MM; this will give you the proper thread size conversion.

Male O.D.

MM

Female I.D.

 

8.5

3/8” -24 UNF

 

8.7

1/8” -28 GAS

 

9.2

1/8” -27 NPSM

3/8” -24 UNF

9.4

 

1/8” -27 GAS

9.6

 

M10x1

10.0

7/16” -20 UNF

1/8” -27 NPTF

10.4

 

 

10.5

M12 x 1.5

7/16” -20 UNF

11.0

 

 

11.4

1/2" -20 UNF

 

11.6

1/4” -19 GAS

M12 x 1.5

12.0

 

 

12.2

¼” -18 NPSM

1/2” -20 UNF

12.5

M14 x 1.5

1/4” -19 UNF

13.0

9/16” -18 UNF

1/4" -18 NPTF

13.9

 

M14 x 1.5

14.0

 

9/16” -18 UNF

14.2

 

 

14.5

M16 x 1.5

 

14.6

5/8” -18 UNF

 

15.1

3/8” -19 GAS

 

15.5

3/8” -18 NPSM

5/8” -18 UNF

15.7

 

M16 x 1.5

16.0

1 1/16” -16 UN

 

16.5

18 x 1.5

3/8” -19 GAS

16.6

 

3/8” -18 NPTF

17.3

 

1 1/16” -16 UNF

17.4

3/4” -16 UNF

M18 x 1.5

18.0

 

 

18.5

M20 x 1.5

 

18.8

1/2" -14 GAS

¾” -16 UNF

19.0

13/16” -16 UNF

Male O.D.

MM

Female I.D.

 

19.2

1/2” -14 NPSM

M20 x 1.5

20.0

 

 

20.3

7/8” – 14 UNF

13/16” -16 UN

20.5

M22 x 1.5

1/2" -14 GASE

20.8

 

 

21.1

5/8” -14 GAS

1/2” -14 NPTF

21.6

 

M22 x 1.5

22.0

 

7/8” -14 UNF

22.2

 

 

22.5

M24 x 1.5

5/8” -14 GAS

22.8

 

 

23.8

1” -14 UNS

M24 x 1.5

24.0

 

 

24.5

M26 x 1.5

 

24.6

3/4” -14 GAS-NPSM

 

24.9

1 1/16” -12 UN

 

25.0

M27 x 2

1” -14 UNS

25.3

 

M26 x 1.5

26.0

 

3/4” -14 NPTF

26.3

 

M27 x 2

26.7

 

 

26.9

 

 

27.0

 

M30 x 2

27.9

1 3/16” -12 UN

1 3/16” -12 UN

28.0

M30 x 2

 

30.0

 

 

30.1

 

 

30.7

1” 11.5 NPSM

 

30.9

1” – 11 GAS

 

31.0

M33 x 2

 

32.1

1 5/16” -12UN

M33 x 2

33.0

 

Male O.D.

MM

Female I.D.

1” -11 GAS

33.2

 

1 5/16” -12 UN

33.3

 

1” -11.5 NPTF

33.8

 

 

34.0

M36 x 2

M36 x 2

36.0

 

 

39.1

1 5/8” -12 UN

 

39.4

1 1/4” -11.5 NPSM

 

39.5

1 1/4” -11 GAS

 

40.0

M42 x 2

1 5/8” -12 UN

41.1

 

1 1/4” -11 GAS

41.7

 

M42 x 2

42.0

 

1 1/4” -11.5 NPTF

42.4

 

 

43.0

M45 x 2

M45 x 2

45.0

 

 

45.2

1 1/2” -11 GAS

 

45.5

1 1/2” -11.5 NPSM

 

45.7

1 7/8” -12 UN

 

46.0

M48 x 2

1 7/8” -12 UN

47.5

 

1 1/2” -11 GAS

47.7

 

M48 x 2

48.0

 

1 1/2” -11.5 NPTF

48.5

 

 

48.8

2” -12 UN

 

50.0

M52 x 2

2” -12 UN

50.7

 

M52 x 2

52.0

 

 

57.0

2” -11 GAS

2” -11 GAS

59.4

 

2” -11.5 NPTF

60.6

 

 

61.2

2 1/2” -12 UN

2 1/2” -12 UN

63.3