Wood Screw Pilot Hole Calculator

Find the correct pilot hole and clearance hole drill bit sizes for wood screws in hardwood and softwood.

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Pilot holes prevent wood from splitting and allow screws to drive straight. Hardwoods need larger pilot holes (75% of screw diameter) than softwoods (55%). The clearance hole in the top piece should match the screw shank so only the threads grip the bottom piece, pulling the joint tight. Always drill pilot holes near board edges and ends.