Screw Pilot Hole Calculator — Correct Drill Bit Sizes
Calculate the correct pilot hole, clearance hole, and countersink diameters for wood screws.
Select the screw gauge for your calculation
Longest dimension of the area
Select the wood type for your calculation
Select based on material and application
How We Calculate This
This calculator determines the correct drill bit sizes for pilot holes, clearance holes, and countersinks based on your screw gauge and wood type.
Pilot hole sizing
Pilot hole = Shank diameter x Wood factor
Softwood factor: 60% | Hardwood: 75% | Plywood: 70% | MDF: 80%
Clearance and countersink
Clearance hole = shank diameter. Countersink diameter = approximately 2x shank diameter.
Frequently Asked Questions
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Last updated: March 2026
All calculations are estimates. Always verify measurements and material quantities before cutting or purchasing.