Machine Screw Size

Number of Threads Per Inch

Minor Dia.

Tap Drills

Clearance Hole Drills

Aluminum, Brass & Plastics

75% Thread 

Stainless Steel, Steels & Iron

50% Thread

All Materials

Close Fit

Free Fit

No. or Dia.

Major Dia.

Drill Size

Decimal Equiv.

Drill Size

Decimal Equiv.

Drill Size

Decimal Equiv.

Drill Size

Decimal Equiv.

7/16

.4375

14

.3499

U

.3680

25/64

.3906

29/64

.4531

15/32

.4687

20

.3762

25/64

.3906

13/32

.4062

28

.3937

Y

.4040

Z

.4130

1/2

.5000

13

.4056

27/64

.4219

29/64

.4531

33/64

.5156

17/32

.5312

20

.4387

29/64

.4531

15/32

.4688

28

.4562

15/32

.4688

15/32

.4688

9/16

.5625

12

.4603

31/64

.4844

33/64

.5156

37/64

.5781

19/32

.5938

18

.4943

33/64

.5156

17/32

.5312

24

.5114

33/64

.5156

17/32

.5312

5/8

.6250

11

.5135

17/32

.5312

9/16

.5625

41/64

.6406

21/32

.6562

18

.5568

37/64

.5781

19/32

.5938

24

.5739

37/64

.5781

19/32

.5938

11/16

.6875

24

.6364

41/64

.6406

21/32

.6562

45/64

.7031

23/32

.6562