Tap-Drill Size Chart

drill bits for tap

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Without a reliable tap drill chart, determining the appropriate drill size for your screws or bolts is next to impossible.

That’s because there are so many factors to take into account including the threads per inch, drill diameter, and the tap drill sizes.

To give you a quick and easy reference that considers all the details, we listed them in a neat and tidy table.

THREAD SIZE

FRACTIONAL (in.)

 

DRILL DIAMETER

 

TAP DRILL SIZE

Coarse Thread

1/64

.0595

No. 53

2-56

.0700

No. 50

3-48

.0785

No. 47

4-40

3/32”

.0890

No. 43

5-40

.1015

No. 38

6-32

7/64”

.1065

No. 36

8-32

.1360

No. 29

10-24

5/32”

.1495

No. 25

12-24

11/64”

.1770

No. 16

1/4-20

13/64”

.2010

No. 7

5/16-18

17/64”

.2570

‘F’

3/8-6

1 7/32”

1.2188

3/8-16

5/16”

.3125

5/16

7/16-14

23/64”

.3680

‘U’

1/2-13

27/64”

.4219

27/64

9/16-12

31/64”

.4844

31/64

5/8-11

17/32”

.5312

17/32

3/4-10

21/32”

.6562

21/32

7/8-9

.7656

49/64

1″-8

.8750

7/8

1-1/2

1.882

1-25/32”

1 1/2 6

1 11/32”

1.3438

1 1/4-7

1 7/64”

1.1094

Fine Thread

0-80

3/64”

.0469

3/64

1-72

.0595

No. 53

2-64

.0700

No. 50

3-56

.0820

No. 45

4-48

.0935

No. 42

5-44

.1040

No. 37

6-40

.1130

No. 33

8-36

.1360

No. 29

10-32

5/32”

.1590

No. 21

12-28

.1820

No. 14

1/4-28

7/32”

.2130

No. 3

5/16-24

.2720

‘I’

3/8-24

21/64”

.3320

‘Q’

7/16-20

25/64”

.3906

25/64

1/2-20

29/64”

.4531

29/64

9/16-18

33/64”

.5156

33/64

5/8-18

37/64”

.5781

37/64

3/4-16

11/16”

.6875

11/16

7/8-14

.8125

13/16

1″-14

.9375

59/64

NS (Special Thread)

7/8 -18 

53/64”

.8281

53/64”

11/16-11

19/32”

.5938

1-14

15/16”

.9375

NEF (Ultra Fine Thread)

5/16-32

9/32”

.2812

8/32”

*Drill sizes are for 75% of the total depth of the thread.

Robert Johnson is a woodworker who takes joy in sharing his passion for creating to the rest of the world. His brainchild, Sawinery, allowed him to do so as well as connect with other craftsmen and women. He has since built an enviable workshop for himself and an equally impressive online accomplishment: an extensive resource site serving old timers and novices alike.
Robert Johnson
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