Wood screw pilot-hole size finder
Pick your screw gauge and what you're drilling into — softwood, hardwood, plywood or MDF — and get the one pilot-hole bit to grab.
Screw size
Covers #4–#14 wood screws — the common range.
Drilling into
Drill this pilot bit
For a #8 screw in softwood
Forgiving to drive — but pilot near the ends so it doesn't split.
Get the gear
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Why this size
Softwood is soft and forgiving — its fibers squeeze around the screw, so it grips well with a smaller pilot hole than hardwood.
Sized to the screw's inner core.
Split-safe — when in doubt, start one size smaller and test on scrap.
Fighting splits? How to keep wood from splitting when screwing and Do deck screws need pilot holes?.
Common questions
How do I know what size pilot hole to drill for a wood screw?
Match the pilot hole to the screw's root diameter — the solid core under the threads — so the threads still grip but the wood isn't forced apart. Pick your screw gauge (#4–#14) and material above and the finder gives you the exact bit as a fraction and in millimetres.
Is the pilot hole different for hardwood and softwood?
Yes. Hardwood is dense and splits more easily, so it takes a slightly larger pilot than softwood for the same screw. Plywood follows the softwood size; MDF follows the hardwood size and fine-thread screws.
Do I always need a pilot hole for wood screws?
Not always — softwood away from edges can often take a screw straight in. Drill one for hardwood, near edges and ends, thin stock, and larger screws. When in doubt, drill one; it's cheap insurance against a split board.
Where these numbers come from
Straight-bit pilot sizes for modern wood screws, sized to the screw’s root diameter — a standard woodworking approach for a hole that grips without splitting — and cross-referenced against widely used charts (Bolt Depot, McFeely’s, WorkshopCalc). We lean slightly larger than the strength-optimized minimums, because for most projects not splitting the board matters more than maximum holding power. Plywood follows softwood; MDF follows hardwood / fine-thread practice.
These are general guidance sizes cross-referenced from common woodworking sources. For structural, load-bearing, or manufacturer-specific work, follow the fastener manufacturer’s or an engineer’s specifications.