Pilot hole calculator for wood screws
A pilot hole lets a wood screw go in straight without splitting the wood; a clearance hole lets it pass freely through the top board so the joint pulls tight. Pick the screw size and the wood to get both drill sizes. Hardwoods such as oak and maple need a slightly larger pilot than softwoods such as pine and fir.
Wood screw pilot hole chart
| Screw | Screw diameter (in) | Pilot, softwood | Pilot, hardwood | Clearance hole |
|---|---|---|---|---|
| #2 | 0.086 | 1/16 in | 5/64 in | 3/32 in |
| #4 | 0.112 | 5/64 in | 3/32 in | 1/8 in |
| #5 | 0.125 | 3/32 in | 7/64 in | 9/64 in |
| #6 | 0.138 | 3/32 in | 7/64 in | 5/32 in |
| #7 | 0.151 | 7/64 in | 1/8 in | 5/32 in |
| #8 | 0.164 | 7/64 in | 1/8 in | 11/64 in |
| #9 | 0.177 | 1/8 in | 9/64 in | 3/16 in |
| #10 | 0.190 | 1/8 in | 9/64 in | 3/16 in |
| #12 | 0.216 | 9/64 in | 5/32 in | 7/32 in |
| #14 | 0.242 | 5/32 in | 3/16 in | 1/4 in |
Typical sizes. Screw makers' own charts can differ by a size; if the box lists a pilot size, use that.
Tips
- Drill the pilot as deep as the screw goes into the lower board. A piece of tape on the bit marks the depth.
- Near the end of a board or in very dense wood, go up one pilot size to avoid splitting.
- Countersink for flat-head screws so the head sits flush; a countersink bit drills the pilot and the countersink in one pass.
- Into end grain or wood filler, screws hold poorly; see can you drill into wood filler for fixing stripped holes.
Print it: printable pilot hole chart. The most common size has its own guide: drill bit size for a #10 screw. For threads in metal, use the tap drill calculator.