What size drill bit do you use for a pilot hole for this screw? Pick your screw and your wood below. You will get a range, not one fake-exact size — because that is what the published charts actually say.
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1 — Screw size
2 — Wood type
The loose hole through the top board only, so the screw pulls the two boards tight together.
Charts can argue. This check cannot. Do it every time, on every screw.
Hold the drill bit up in front of the screw, across the smooth shank between the threads. The bit should cover the shank but the threads should still peek out on both sides.
Too small a hole splits the wood; too big a hole leaves the threads nothing to bite.
The bit is thinner than the shank. The screw has to force the wood apart.
The bit covers the shank. The threads still peek out on both sides, ready to bite.
The bit is as wide as the threads. There is nothing left for the threads to grip.
Every size in one place. Each pilot size is a range — the low and high ends are what different published charts give for that screw and wood.
| Screw | Pilot — softwood | Pilot — hardwood | Clearance hole |
|---|
A screw is a wedge. As you drive it in, it pushes the wood apart.
Near the end of a board, or in hardwood, that push can split the wood. A pilot hole makes room for the smooth shank first, so the screw does not have to force its way in. The threads still cut into the sides of the hole — and that is what holds.
No pilot hole is needed for every screw in soft wood. But near an end, near an edge, or in anything hard, it is cheap insurance.
Make the pilot hole a little shorter than the screw length, so the tip still has solid wood to bite into.
Drill straight in, not at an angle, or the screw will try to follow the crooked hole.
A countersink lets the head sit flush. It also stops the top board from jacking apart as the screw pulls tight.
Sources: Engineering ToolBox — wood screw pilot hole table; Albany County Fasteners — Wood Screw Pilot Hole Guide. Sizes on this page are the range across those published charts.
Checked November 2026.