Hole Size Data for Self-Tapping Screws

Suggested Test Plate Thicknesses & Hole Sizes
for Types 1 - 23 - F
Nominal Screw Size
& Thread Pitch		 Thickness Hole Size
Gage Max Min Drill Size Hole Diam.
2-56 18 .0800 .0760 49 0.0730
4-40 18 .1110 .1070 41 0.0960
5-40 18 .1110 .1070 37 0.1010
6-32 14 .1425 .1385 31 0.1200
8-32 14 .1905 .1845 26 0.1470
10-24 1/8 .1905 .1845 17 0.1730
10-32 1/8 .1905 .1845 16 0.1770
12-24 1/8 .1905 .1845 8 0.1990
1/4-20 3/16 .2530 .2470 1 0.2280
5/16-18 3/16 .3155 .3095 L 0.2900
3/8-16 3/16 .3780 .3720 T 0.3580
1/2-13 3/16 .471 .443 29/64 0.4531
Suggested Test Plate Thicknesses & Hole Sizes
for Types AB - B - 25
Nominal Screw Size & No. of Threads per Inch Thickness Hole Size
Gage Max Min Drill Size Hole Diam.
2-32 18 .0500 .0460 48 .0760
3-28 18 .0500 .0460 46 .0810
4-24 18 .0500 .0460 44 .0860
5-20 18 .0500 .0460 36 .1065
6-20 14 .0770 .0730 32 .1160
7-19 14 .0770 .0730 30 .1285
8-18 14 .1270 .1230 29 .1360
10-16 1/8 .1270 .1230 21 .1590
12-14 1/8 .1270 .1230 3/16 .1875
1/4-14 3/16 .1905 .1845 5.5 mm .2165
5/16-12 3/16 .1905 .1845 I .2720
3/8-12 3/16 .1905 .1845 21/64 .3281
Suggested Hole Sizes for Type-A
Nominal Screw Size Hole Size
Drill Size Hole Diam.
6-18 #32 0.1160
7-16 #30 0.1285
8-15 #29 0.1360
10-12 #21 0.1590
12-11 3/16 0.1875
20-9 L 0.2900
24-9 11/32 0.3438
Suggested Hole Sizes for High-Low Screws
Nominal Screw Size & Number
of Threads per Inch		 Pilot Hole Diameter
Flexural Modulus of Plastic
Up to
200,000 P.S.I.		 200,000 - 400,000 P.S.I.
2-32 .0670 .0700
3-28 .0730 .0781
4-24 .0810 .0860
5-20 .0935 .0995
6-19 .1015 .1100
7-19 .1200 .1250
8-18 .1200 .1285
10-16 .1360 .1440
12-16 .1570 .1660
1/4-15 .1890 .2010
5/16-14 .2380 .2500
Recommended Hole Sizes
for Type-U Drive Screws
Screw Size Drill Size # Hole Diameter
00 55 .052
0 51 .067
2 44 .086
4 37 .104
6 31 .120
7 29 .136
8 27 .144
10 20 .161
12 11 .191
14 2 .221