Reference chart
Screw Pilot Hole Chart
Typical pilot, shank and countersink bit sizes for common wood screws, with separate pilot holes for hardwood and softwood.
A pilot hole stops the wood from splitting and lets the screw pull the joint tight. Drill the pilot in the receiving piece and a slightly larger clearance (shank) hole in the top piece so it pulls down. Hardwoods need a larger pilot than softwoods. These are typical fractional-inch bit sizes; go up a size in very dense woods.
| Screw | Pilot, hardwood | Pilot, softwood | Shank / clearance |
|---|---|---|---|
| #2 | 1/16 | 3/64 | 5/64 |
| #4 | 1/16 | 3/64 | 7/64 |
| #6 | 5/64 | 1/16 | 9/64 |
| #8 | 3/32 | 5/64 | 11/64 |
| #10 | 7/64 | 3/32 | 3/16 |
| #12 | 1/8 | 7/64 | 7/32 |
| 1/4" | 11/64 | 9/64 | 17/64 |
Values are typical and vary by screw brand and wood density; check the densest woods on the Janka chart and size up if needed.
Related calculators
Sources
These calculators are for planning and estimation. Engineering results (shelf sag, wood movement) use published average material properties; real boards vary by grade, grain, moisture and defects. Verify load-bearing designs with a professional.