Pilot Hole & Drill Bit Sizing
To ensure the best results when installing screws, it is often necessary to pre-drill a pilot hole. Self-drilling screws are designed for this task and can drill their own holes into metal or plastic without requiring additional tools. For other types of fasteners such as Type B Tapping, Type F Thread Cutting & Forming Screws, and even sharp pointed type A/AB Self Drilling Screws – having an accurately sized pilot hole will prevent splitting wood or distorting metal surfaces while driving them in place. Our charts outline standard drill bit sizes to obtain successful installation outcomes every time!
TYPE AB SELF-TAPPING SCREW
TYPE B SELF-TAPPING SCREW
TYPE 25 SELF-CUTTING SCREW
| 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 SCREW
| 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 THREAD-CUTTING SCREW
TYPE 1 THREAD-CUTTING SCREW
TYPE 23 THREAD-CUTTING SCREW
| Screw Size | Screw Threads per Inch | 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 SCREW
| Screw Size | Screw Threads per Inch | Recommended Hole Diameter for Ductile Material | Drill Bit Size | Recommended Hole Diameter for Brittle Material | 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" |
PLASTITE THREAD FORMING SCREWS
| Screw Size | Screw Threads per Inch | Recommended Hole Diameter for Ductile Material | Drill Bit Size | Recommended Hole Diameter for Brittle Material | Drill Bit Size |
|---|---|---|---|---|---|
|
#2 |
28 |
0.0760" |
#48 |
0.0810" |
#46 |
|
#3 |
24 |
0.0890" |
#43 |
0.0940" |
3/32" |
|
#4 |
20 |
0.1000" |
#39 |
0.1060" |
#36 |
|
#5 |
20 |
0.1110" |
#34 |
0.1160" |
#32 |
|
#6 |
19 |
0.1200" |
#31 |
0.1250" |
1/8" |
|
#7 |
19 |
0.1360" |
#29 |
0.1406" |
9/64" |
|
#8 |
16 |
0.1495" |
#25 |
0.1570" |
#22 |
|
#10 |
14 |
0.1770" |
#16 |
0.1850" |
#13 |
|
#12 |
11 |
0.1960" |
#9 |
0.2055" |
#5 |
|
1/4" |
10 |
0.2210" |
#2 |
0.2420" |
#C |
|
5/16" |
9 |
0.2900" |
#L |
0.3020" |
#N |