Tap Chart - UNC/UNF Threads

Tap size

NF/NC UNF/UNC

Threads per inch

Basic major dia (inches)

Basic effective dia (inches) Basic minor dia of ext. threads (inches) Basic minor dia of int. threads (inches)

Drill size

0-80

UNF

80

.0600

.0519 .0447 .0465

3/64

1-64 UNC 64 .0730 .0629 .0538 .0561 #54

2-56

UNC

56

.0860

.0744 .0641 .0667

#50

2-64

UNF

64

.0860

.0759 .0668 .0691

#50

4-40

UNC

40

.1120

.0958 .0813 .0849

#43

4-48

UNF

48

.1120

.0985 .0864 .0894

#42

5-40

UNC

40

.1250

.1088 .0943 .0979

#38

5-44

UNF

44

.1250

.1102 .0971 .1004

#37

6-32

UNC

32

.1360

.1177 .0997 .1042

#36

6-40

UNF

40

.1360

.1218 .1073 .1109

#33

8-32

UNC

32

.1640

.1437 .1257 .1302

#29

8-36

UNF

36

.1640

.1460 .1299 .1339

#29

10-24

UNC

24

.1900

.1629 .1389 .1449

#25

10-32

UNF

32

.1900

.1697 .1517 .1562

#21

1/4-20

UNC

20

.2500

.2175 .1887 .1959

#7

1/4-28

UNF

28

.2500

.2268 .2062 .2113

#3

5/16-18

UNC

18

.3125

.2764 .2443 .2524

F

5/16-24

UNF

24

.3125

.2854 .2614 .2674

I

3/8-16

UNC

16

.3750

.3344 .2983 .3073

5/16

3/8-24

UNF

24

.3750

.3479 .3239 .3299

Q

7/16-14

UNC

14

.4375

.3911 .3499 .3602

U

7/16-20

UNF

20

.4375

.4050 .3762 .3834

25/64

1/2-13

UNC

13

.5000

.4500 .4056 .4167

27/64

1/2-20

UNF

20

.5000

.4675 .4387 .4459

29/64

9/16-12

UNC

12

.5625

.5084 .4603 .4723

31/64

9/16-18

UNF

18

.5625

.5264 .4943 .5024

33/64

5/8-11

UNC

11

.6250

.5660 .5135 .5266

17/32

5/8-18

UNF

18

.6250

.5869 .5568 .5649

37/64

3/4-10

UNC

10

.7500

.6650 .6273 .6417

21/32

3/4-16

UNF

16

.7500

.7094 .6733 .6823

11/16

7/8-9

UNC

9

.8750

.8028 .7387 .7547

49/64

7/8-14

UNF

14

.8750

.8286 .7874 .7977

13/16

1-8

UNC

8

1.000

.9188 .8466 .8647

7/8

1-14

UNF

14

1.000

.9459 .8978 .9098

15/16

1 1/8-7

UNC

7

1.1250

1.0322 .9497 .9704

63/64

1 1/8-12

UNF

12

1.1250

1.0709 1.0228 1.0348

1 3/64

1 1/4-7 UNC 7 1.2500 1.1572 1.0747 1.0954 1 7/64
1 3/8-6 UNC 6 1.3750 1.2667 1.1705 1.1946 1 13/64
1 1/2-6 UNC 6 1.5000 1.3917 1.2955 1.3196 1 11/32
1 3/4-5 UNC 5 1.7500 1.6201 1.5046 1.5335 1 35/64
2-4.5 UNC 4 1/2 2.0000 1.8557 1.7274 1.7594 1 25/32