WhatDrillBit is a free reference tool that helps DIYers and woodworkers find the right pilot-hole drill bit for a given wood screw and material — so you drill a hole that grips without splitting the board.
How it works
Pick your screw gauge (#4–#14) and what you're drilling into — softwood, hardwood, plywood or MDF — and the tool gives you the exact pilot bit, as a fraction, a decimal and millimetres, with a plain-language note on why.
Where the numbers come from
Sizes are straight-bit pilot dimensions for modern wood screws, based on the screw's root (inner) diameter — the practical basis for a pilot hole. We cross-reference them against established charts (Bolt Depot, McFeely's and WorkshopCalc) and use a split-safe calibration that runs slightly larger than the strength-optimized minimums, because for most projects not splitting the board matters more than maximum holding power.
We only publish sizes we can stand behind. Where sources disagree we lean split-safe, and we don't invent numbers we can't verify.
Honest by design
WhatDrillBit is a straightforward reference, not a personality. We don't claim decades in a workshop — the value is in getting the numbers right and explaining them plainly, so you can drill with confidence. Pilot-hole sizing still depends on real-world variables, so treat the tool as a well-researched starting point: when in doubt, start one size smaller and test on scrap.