Tap size
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
80
.0600
3/64
2-56
56
.0860
#50
2-64
64
4-40
40
.1120
#43
4-48
48
#42
5-40
.1250
#38
5-44
44
#37
6-32
32
.1360
#36
6-40
#33
8-32
.1640
#29
8-36
36
10-24
24
.1900
#25
10-32
#21
1/4-20
20
.2500
#7
1/4-28
28
#3
5/16-18
18
.3125
F
5/16-24
I
3/8-16
16
.3750
5/16
3/8-24
Q
7/16-14
14
.4375
U
7/16-20
25/64
1/2-13
13
.5000
27/64
1/2-20
29/64
9/16-12
12
.5625
31/64
9/16-18
33/64
5/8-11
11
.6250
17/32
5/8-18
37/64
3/4-10
10
.7500
21/32
3/4-16
11/16
7/8-9
9
.8750
49/64
7/8-14
13/16
1-8
8
1.000
7/8
1-14
15/16
1 1/18-7
7
1.1250
63/64
1 1/8-12
1 3/64