TAP SIZE 

DRILL SIZE

#0-80 

3/64" 

#1-64

#53 

#2-56 

#51 

#3-48 

5/64" 

#4-40 

#43 

#5-40 

#39 

#6-32 

#36 

#8-32 

#29 

#10-24 

#25 

#12-24 

#17 

1/4-20 

#7 

5/16-18 

F 

3/8-16 

5/16 

7/16-14

U 

1/2-13 

27/64 

9/16-12 

31/64 

5/8-11 

17/32 

3/4-10 

21/32 

7/8-9 

49/64 

1"-8 

7/8 

1-1/8-7 

63/64 

1-1/4-7 

1-7/64 

1-1/2-6 

1-11/32 

1-3/4-5 

1-35/64 

2"-4-1/2 

1-25/32

INCH SIZES - NATIONAL FINE

TAP SIZE 

DRILL SIZE

#1-72 

#53

#2-64 

#50

#3-56 

#46

#4-48 

#42

#5-44 

#37

#6-40 

#33

#8-36 

#29

#10-32 

#21

#12-28 

#15

1/4-28 

#3

5/16-24 

I

3/8-24 

Q

7/16-20 

W

1/2-20 

29/64

9/16-18 

33/64

5/8-18 

37/64

3/4-16 

11/16

7/8-14 

13/16

1"-14 

15/16

1-1/8-12 

1-3/64

1-1/4-12 

1-11/64

1-1/2-12 

1-27/64

1-3/4-12 

1-43/64

2"-12 

1-59/64

TAPER PIPE SIZES - NPT

TAP SIZE 

DRILLSIZE

1/8-27 

R

1/4-18 

7/16

3/8-18 

37/64

1/2-14 

23/32

3/4-14 

59/64

1"-11-1/2 

1-5/32

1-1/4-11-1/2 

1-1/2

1-1/2-11-1/2 

1-47/64

2"-11-1/2

 2-7/32

2-1/2-8 

2-5/8

3"-8 

3-1/4

3-1/2-8 

3-3/4

4"-8 

4-1/4

STRAIGHT PIPE SIZES - NPS

TAP SIZE 

Drill SIZE

1/8-27 

S

1/4-18 

29/64

3/8-18 

19/32

1/2-14 

47/64

3/4-14 

15/16

1"-11-1/2 

1-3/16

1-1/4-11-1/2 

1-33/64

1-1/2-11-1/2

1-3/4

2"-11-1/2

2-7/32

2-1/2-8 

2-21/32

3"-8 

3-9/32

3-1/2-8 

3-25/32

4"-8 

4-9/32

TAP SIZE

DRILL SIZE

1mm x .25

.75mm

1.1 x .25

.85

1.2 x .25

.95

1.4 x .3

1.1

1.6 x .35

1.25

1.7 x .35

1.3

1.8 x .35

1.45

2 x .4

1.6

2.2 x .45

1.75

2.5 x .45

2.05

3 x .5

2.5

3.5 x .6

2.9

4 x .7

3.3

4.5 x .75

3.7

5 x .8

4.2

6 x 1

5

7 x 1

6

8 x 1.25

6.8

9 x 1.25

7.8

10 x 1.5

8.5

11 x 1.5

9.5

12 x 1.75

10.2

14 x 2

12

16 x 2

14

18 x 2.5

15.5

20 x 2.5

17.5

22 x 2.5

19.5

24 x 3

21

27 x 3

24

30 x 3.5

26.5

33 x 3.5

29.5

36 x 4

32

39 x 4

35

METRIC FINE SIZES

TAP SIZE

DRILL SIZE

4 mm x .35

3.6mm

4 x .5

3.5

5 x .5

4.5

6 x .5

5.5

6 x .75

5.25

7 x .75

6.25

8 x .5

7.5

8 x .75

7.25

8 x 1

7

9 x 1

8

10 x .75

9.25

10 x 1

9

10 x 1.25

8.8

11 x 1

10

12 x .75

11.25

12 x 1

11

12 x 1.5

10.5

14 x 1

13

14 x 1.25

12.8

14 x 1.5

12.5

16 x 1

15

16 x 1.5

14.5

18 x 1

17

18 x 2

16

20 x 1

19

20 x 1.5

18.5

20 x 2

18

22 x 1

21

22 x 1.5

20.5

22 x 2

20

24 x 1.5

22.5

24 x 2

22

26 x 1.5

24.5

27 x 1.5

25.5

27 x 2

25

28 x 1.5

26.5

30 x 1.5

28.5

30 x 2

28

33 x 2

31

36 x 3

33

39 x 3

36