What Size Pilot Hole For a 12 Screw
0.125" in softwood, 0.1406" in hardwood
- #12 wood screw (shank diameter 0.216")
Methodpilot hole sized to roughly the screw's root diameter in softwood, slightly larger in denser hardwood to avoid splitting.
Size up for wood close to an edge or end grain, where splitting risk is highest regardless of the general-purpose figure.
A #12 wood screw wants a 0.125" pilot hole in softwood or 0.1406" in hardwood — an even 1/8" and 9/64" respectively — the heaviest common wood-screw gauge before most builders switch to purpose-made structural screws instead.
Why this one specifically
At #12, a standard wood screw is approaching the point of diminishing returns: the shank is thick enough that hand-driving without a pilot hole is essentially never an option even in softwood, and hardwood without a correctly-sized pilot risks splitting the workpiece outright rather than just stripping the hole. For genuinely structural connections beyond this size — deck ledgers, heavy hardware, anything rated for real load — most builders move to dedicated structural screws (GRK, Spax and similar) engineered for that job specifically, rather than reaching for a still-heavier traditional wood screw gauge.
What moves the number
Pilot hole size still scales with gauge the same way it does at every lighter size, but at #12 the countersink also becomes worth checking separately — a screw this size seats a visibly larger head, and getting the countersink diameter wrong is now as noticeable as getting the pilot hole wrong.