Pre Tap Drill Size

Inch Form Tap

Tap
Drill Size
Decimal Equivalent
3/4-16
23/32
0.7188
3/4-10
45/64
0.7031
5/8-18
15.25mm
0.6004
5/8-11
14.75mm
0.5807
9/16-18
13.50mm
0.5315
9/16-12
17/32
0.5312
1/2-20
12.25mm
0.4823
1/2-13
15/32
0.4682
7/16-20
Z
0.4130
7/16-14
Y
0.4040
3/8-24
T
0.3580
3/8-16
S
0.3480
5/16-24
M
0.2950
5/16-18
L
0.2900
1/4-28
15/64
0.2340
1/4-20
1
0.2280
12-28
7
0.2010
12-24
8
0.1990
10-32
16
0.1770
10-24
11/64
0.1719
8-36
24
0.1520
8-32
25
0.1495
6-40
3.25mm
0.1280
6-32
1/8
0.1250
5-44
2.90mm
0.1142
5-40
33
0.1130
4-48
2.60
0.1023
4-40
38
0.1015
3-56
2.30mm
0.0905
3-48
43
0.0890
2-64
47
0.0785
2-56
5/64
0.0781
1-72
51
0.0670
1-64
51
0.0670
0-80
54
0.0550