Wood Screw Pilot Hole Sizes

Screw Size Hard Wood Soft Wood Countersink Size
Tapered Bit Straight Bit Tapered Bit Straight Bit
2 3/32 1/16 5/64 1/16 1/4
3 7/64 5/64 3/32 1/16 1/4
4 7/64 5/64 3/32 1/16 1/4
5 1/8 3/32 7/64 5/64 5/16
6 9/64 7/64 1/8 3/32 5/16
7 5/32 7/64 9/64 3/32 5/16
8 11/64 1/8 5/32 7/64 3/8
9 3/16 9/64 11/64 1/8 3/8
10 13/64 9/64 3/16 1/8 7/16
12 7/32 5/32 13/64 9/64 7/16
14 1/4 11/64 15/64 5/32 1/2
16 9/32 3/16 17/64 11/64 9/16
18 5/16 7/32 19/64 13/64 5/8
20 21/64 15/64 5/16 7/32 3/4
24 3/8 17/64 3/8 1/4 3/4