Pilot hole size for a #8 screw
The #8 is the all-purpose wood screw — the default for cabinets, shelves, furniture, deck hardware and general construction. If a project doesn't name a size, it's usually a #8.
Drilling a pilot hole first stops the screw from splitting the board and makes it far easier to drive straight. Here's the right pilot bit for a #8 in every common material.
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Covers #4–#14 wood screws — the common range.
Pilot hole sizes for a #8 screw
Forgiving to drive — but pilot near the ends so it doesn't split.
Splits easily — don't skip the pilot, and drive the screw slowly.
Back it with scrap so it won't splinter on the exit side.
Dense — drill slowly and stay in from the edge, or it blows out.
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How to size a pilot hole
A pilot hole is a small guide hole you drill before the screw. Size it to the screw's root diameter — the solid core under the threads — and the threads still bite while the board isn't forced apart and split.
Split-safe — when in doubt, start one size smaller and test on scrap.
Common questions
What size hole should I predrill for a #8 screw?
For a #8 screw, drill a 7/64" (2.8 mm) pilot hole in softwood, or 1/8" (3.2 mm) in hardwood. Plywood uses the softwood size; MDF uses the hardwood size.
What drill bit do I use for a #8 screw?
Use a 7/64" bit for softwood and a 1/8" bit for hardwood. Those match the screw's root (inner) diameter, so the threads still grip but the wood isn't forced apart.
Is the pilot hole bigger in hardwood for a #8 screw?
Yes. Hardwood splits more easily, so a #8 screw takes a slightly larger 1/8" pilot hole versus 7/64" in softwood.
Do I need a pilot hole for a #8 screw in MDF?
Yes. MDF is dense and blows out near edges. Drill the hardwood size (1/8", 3.2 mm), go slowly, keep back from the edge, and use fine-thread screws.
Full pilot-hole chart
| Screw | Softwood | Hardwood |
|---|---|---|
| #4 | 1/16"1.6 mm | 5/64"2.0 mm |
| #6 | 5/64"2.0 mm | 3/32"2.4 mm |
| #8 | 7/64"2.8 mm | 1/8"3.2 mm |
| #10 | 1/8"3.2 mm | 9/64"3.6 mm |
| #12 | 9/64"3.6 mm | 5/32"4.0 mm |
| #14 | 5/32"4.0 mm | 11/64"4.4 mm |
Softwood — pine, fir, cedar, spruce · Plywood uses the Softwood column.
Hardwood — oak, maple, walnut, birch · MDF uses the Hardwood column (use fine-thread screws).
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.