FullCalculator

Wood Screw Pilot Hole Calculator

Pilot Hole Size

Calculate pilot and clearance hole sizes for wood screws

Formula

Pilot Hole = ~65% of screw shank (softwood) or ~75% (hardwood) | Clearance Hole = Shank Diameter + 1/64 inch

Frequently Asked Questions

Why do I need a pilot hole?
Pilot holes prevent wood from splitting, make driving screws easier, and ensure screws go in straight. They are especially important near edges and in hardwoods.
What is a clearance hole?
A clearance hole is drilled through the top piece so the screw passes freely. This ensures the screw pulls the top piece tight against the bottom piece.

You may also need