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"

1-12

UNF

12"

1.000"

.9459" .8978" .9098"

59/64"

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"