Wood screws are sized by gauge number — the higher the number, the thicker the screw. This chart gives the diameter and a pilot-hole size for softwood.
| Gauge | Diameter | Pilot (softwood) |
|---|---|---|
| #6 | 0.138 in | 5/64 in |
| #8 | 0.164 in | 3/32 in |
| #10 | 0.190 in | 7/64 in |
| #12 | 0.216 in | 1/8 in |
| #14 | 0.242 in | 9/64 in |
Drill pilots in hardwood. A pilot hole prevents splitting and makes driving easier. In hardwoods, size the pilot to the screw’s solid core; in softwoods you can often skip it for smaller screws.
See the Nail Size Chart and Fastener Size Chart.