RECOMMENDED DRILL SIZES

FOR

SELF-TAPPING SCREWS (SHEET METAL)

Self-Tapping Screw Size
Major Thread Diameter
Minor Thread Diameter
For Heavy Metals
For Light Metals

No.

Threads per Inch

O.D.

Max.

Mean 
Min.

Max.

 

Mean
Min.
Drill Size
Drill Size
2
32
.086
.088
.0850
.082
.064
.0620
.060
49
.0730
49
.0730
4
24
.112
.114
.1110
.108
.086
.0840
.082
41
.0960
41
.0960
5
20
.125
.130
.1265
.123
.094
.0920
.090
36
.1065
36
.1065
6
20
.138
.139
.1355
.132
.104
.1015
.099
32
.1160
32
.1160
7
19
.151
.154
.1505
.147
.115
.1120
.109
30
.1285
30
.1285
8
18
.164
.166
.1625
.159
.122
.1190
.116
28
.1405
29
.1360
10
16
.190
.189
.1855
.182
.141
.1380
.135
20
.1610
21
.1590
12
14
.216
.215
.2115
.208
.164
.1605
.157
13
.1850
14
.1820
1/4
14
.250
.246
.2415
.237
.192
.1885
.185
3
.2130
4
.2090
5/16
12
.313
.315
.3105
.306
.244
.2400
.236
I
.2720
H
.2660
3/8
12
.375
.380
.3755
.371
.309
.3040
.299
R
.3390
Q
.3320

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