Look up the correct pilot, clearance, and countersink hole size for any screw gauge.
| Gauge | Shank dia. | Softwood pilot | Hardwood pilot | Clearance hole | Countersink |
|---|---|---|---|---|---|
| #2 | 0.086" | 1/16" | 3/64" | 3/32" | 1/4" |
| #3 | 0.099" | 5/64" | 1/16" | 7/64" | 1/4" |
| #4 | 0.112" | 5/64" | 1/16" | 1/8" | 1/4" |
| #5 | 0.125" | 3/32" | 5/64" | 9/64" | 5/16" |
| #6 | 0.138" | 7/64" | 3/32" | 9/64" | 5/16" |
| #7 | 0.151" | 1/8" | 7/64" | 5/32" | 3/8" |
| #8 | 0.164" | 9/64" | 1/8" | 11/64" | 3/8" |
| #9 | 0.177" | 5/32" | 9/64" | 3/16" | 7/16" |
| #10 | 0.190" | 3/16" | 5/32" | 13/64" | 7/16" |
| #12 | 0.216" | 7/32" | 3/16" | 1/4" | 1/2" |
| #14 | 0.242" | 1/4" | 7/32" | 17/64" | 1/2" |
#8 highlighted — the most common cabinet and furniture screw gauge.
| Size | Screw dia. | Softwood pilot | Hardwood pilot | Clearance hole |
|---|---|---|---|---|
| M3 | 3.0 mm | 2.0 mm | 2.5 mm | 3.2 mm |
| M4 | 4.0 mm | 2.5 mm | 3.0 mm | 4.2 mm |
| M5 | 5.0 mm | 3.0 mm | 4.0 mm | 5.2 mm |
| M6 | 6.0 mm | 4.0 mm | 5.0 mm | 6.4 mm |
| M8 | 8.0 mm | 5.0 mm | 6.5 mm | 8.4 mm |
| M10 | 10.0 mm | 6.5 mm | 8.5 mm | 10.5 mm |
Drilled into the receiving piece (the wood the screw threads into). Smaller than the screw threads — allows the threads to bite and grip. In softwood you can often skip this; in hardwood it is always required to prevent splitting and snapped screws.
Drilled through the first (clamping) piece. Equal to or very slightly larger than the shank diameter — allows the screw to slide through freely so the head can pull the joint tight. Without a clearance hole, the screw clamps both pieces and the joint won't close fully.
A tapered (countersink) or flat-bottomed (counterbore) recess that allows the screw head to sit flush with or below the surface. Countersink is for flat-head screws; counterbore is for pan or dome-head screws with a plug over the top.