Pilot Hole Size Chart
By Emmanuel Admin •
July 16, 2021
Posted in Charts
Type AB Self-Tapping Screws, Type B Self-Tapping Screws, Type 25 Thread Cutting Screws. (All require the same pilot hole and drill bit sizes.)
| Screw Size |
Screw Threads per Inch |
Recommended Hole Diameter |
Drill Bit Size |
| #2 |
32 |
0.0760" |
#48 |
| #3 |
28 |
0.0810" |
#46 |
| #4 |
24 |
0.0860" |
#44 |
| #5 |
20 |
0.1065" |
#36 |
| #6 |
20 |
0.1160" |
#32 |
| #7 |
19 |
0.1285" |
#30 |
| #8 |
18 |
0.1360" |
#29 |
| #10 |
16 |
0.1590" |
#21 |
| #12 |
24 |
0.1875" |
3/16" |
| 1/4" |
14 |
0.2188" |
7/32" |
| 5/16" |
12 |
0.2720" |
I |
| 3/8" |
12 |
0.3281" |
21/64" |
Type A Self-Tapping Screws
| Screw Size |
Screw Threads per Inch |
Recommended Hole Diameter |
Drill Bit Size |
| #2 |
32 |
0.0760" |
#48 |
| #3 |
28 |
0.0810" |
#46 |
| #4 |
24 |
0.0860" |
#44 |
| #5 |
20 |
0.1065" |
#36 |
| #6 |
18 |
0.1160" |
#32 |
| #7 |
16 |
0.1285" |
#30 |
| #8 |
15 |
0.1360" |
#29 |
| #10 |
12 |
0.1590" |
#21 |
| #12 |
11 |
0.1875" |
3/16" |
| #14 / 1/4" |
10 |
0.2188" |
7/32" |
| 5/16" |
9 |
0.2900" |
L |
| 3/8" |
9 |
0.3438" |
11/32" |
Type F, Type 1, Type 23 Thread Cutting Screws
| Screw Size-TPI |
Recommended Hole Diameter |
Drill Bit Size |
| 2-56 |
0.0730" |
#49 |
| 3-48 |
0.0810 |
#46 |
| 4-40 |
0.0960" |
#41 |
| 5-40 |
0.1010" |
#37 |
| 6-32 |
0.1200" |
#31 |
| 8-32 |
0.1470" |
#26 |
| 10-24 |
0.1730" |
#17 |
| 10-32 |
0.1770" |
#16 |
| 12-24 |
0.1990" |
#8 |
| 1/4-20 |
0.2280" |
#1 |
| 5/16-18 |
0.2900" |
L |
| 3/8-16 |
0.3580" |
T |
| 1/2-13 |
0.4531" |
29/64" |
High Low Thread Forming Screws
| Screw Size |
Threads Per Inch |
Recommended Hole Diameter for Material with Flexural Modulus of Up to 200,000 P.S.I. |
Drill Bit Size |
Recommended Hole Diameter for Material with Flexural Modulus of Over to 200,000 P.S.I. |
Drill Bit Size |
| #2 |
32 |
0.067" |
#51 |
0.070" |
#50 |
| #3 |
28 |
0.073" |
#49 |
0.078" |
5/64" |
| #4 |
24 |
0.081" |
#46 |
0.086" |
#44 |
| #5 |
20 |
0.094" |
#42 |
0.100" |
#39 |
| #6 |
19 |
0.102" |
#38 |
0.110" |
#35 |
| #7 |
19 |
0.120" |
#31 |
0.125" |
1/8" |
| #8 |
18 |
0.120" |
#31 |
0.129" |
#30 |
| #10 |
16 |
0.136" |
#29 |
0.144" |
#27 |
| #12 |
16 |
0.157" |
#22 |
0.166" |
#19 |
| #14 / 1/4" |
15 |
0.189" |
#12 |
0.201" |
#7 |
| 5/16" |
14 |
0.238" |
#B |
0.250" |
1/4" (E) |
U-Drive or Hammer Drive Screws
| Screw Size-TPI |
Recommended Hole Diameter |
Drill Bit Size |
| 00 |
0.052" |
#55 |
| 0 |
0.067" |
#51 |
| 2 |
0.086" |
#44 |
| 4 |
0.104" |
#37 |
| 6 |
0.120" |
#31 |
| 7 |
0.136" |
#29 |
| 8 |
0.144" |
#27 |
| 10 |
0.161" |
#20 |
| 12 |
0.191" |
#11 |
| 14 |
0.221" |
#2 |
Thread Forming Screws for Plastics
| Screw Size |
Screw Threads Per Inch |
Soft Ductile Materials |
Brittle Materials |
| #0 |
40 |
0.0498" |
0.0490" |
| #2 |
28 |
0.0760" |
0.0800" |
| #3 |
24 |
0.0880" |
0.0940" |
| #4 |
20 |
0.1000" |
0.1060" |
| #5 |
20 |
0.1110" |
0.1170" |
| #6 |
19 |
0.1220" |
0.1280" |
| #7 |
18 |
0.1340" |
0.1420" |
| #8 |
16 |
0.1490" |
0.1580" |
| #9 |
15 |
0.1620" |
0.1720" |
| #10 |
14 |
0.1750" |
0.1850" |
| #12 |
11 |
0.1950" |
0.2050" |
| #14 or 1/4" |
10 |
0.2240" |
0.2400" |
| 5/16" |
9 |
0.2860" |
0.3030" |
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