Pilot hole chart for wood screws
The drill for each screw size, in hardwood and in softwood, and the clearance hole for the piece on top. No standard sets these, so each size is the median of the published charts (four or five per size), and the column under it is the span they cover. Sizes are for a straight drill bit.
| Screw | Pilot, hardwood | Pilot, softwood | Clearance hole |
|---|---|---|---|
| #4 | 5/64 in2 mm · charts span 0.063–0.078 inMedian of 4 sources | 3/64 or 1/16 in1.4 mm · charts span 0.047–0.063 inMedian of 4 sources | 7/64 in2.8 mm · all charts agreeMedian of 3 sources |
| #6 | 3/32 in2.4 mm · charts span 0.078–0.109 inMedian of 5 sources | 5/64 in2 mm · charts span 0.063–0.094 inMedian of 5 sources | 9/64 in3.6 mm · all charts agreeMedian of 3 sources |
| #8 | 7/64 or 1/8 in3 mm · charts span 0.094–0.125 inMedian of 5 sources | 3/32 in2.4 mm · charts span 0.078–0.109 inMedian of 5 sources | 11/64 in4.4 mm · all charts agreeMedian of 3 sources |
| #10 | 1/8 in3.2 mm · charts span 0.109–0.141 inMedian of 5 sources | 7/64 in2.8 mm · charts span 0.094–0.125 inMedian of 5 sources | 3/16 in4.8 mm · charts span 0.188–0.203 inMedian of 3 sources |
| #12 | 9/64 or 5/32 in3.8 mm · charts span 0.125–0.156 inMedian of 5 sources | 1/8 in3.2 mm · charts span 0.094–0.141 inMedian of 5 sources | 7/32 in5.6 mm · all charts agreeMedian of 3 sources |
| #14 | 5/32 or 11/64 in4.2 mm · charts span 0.141–0.188 inMedian of 4 sources | 9/64 in3.6 mm · charts span 0.109–0.156 inMedian of 4 sources | 1/4 in6.4 mm · all charts agreeOnly two sources publish this: McFeely’s and Engineering ToolBox |
How to use it
Drill the pilot hole in the piece the screw threads into, and the clearance hole through the piece being fastened down, so the screw pulls the two together. Where the median falls exactly between two drills the chart names both: the USDA Wood Handbook ties a bigger lead hole to denser wood, so lean to the larger in dense hardwood. The charts differ by a drill size or two, so for a fit that matters, try a hole in a scrap of the same wood.
Charts counted: Engineers Edge, Engineering ToolBox, McFeely’s, MISUMI and Bob Vila (for #6 to #12). WoodBin’s pilot columns match Engineers Edge row for row, so it counts once, and only for the clearance hole. Tapered-bit columns are left out: a tapered bit is a different tool.
For one screw at a time, with the countersink, use the pilot hole calculator. Lag screws follow a different rule: see the lag screw pilot hole chart.
Sources
- Engineers Edge, ANSI flat, pan and oval head wood screws per ANSI B18.6.1, size table; pilot hole drill sizes for wood screws, read 2026-11-07
- Engineering ToolBox, US wood screws: pilot holes, shank clearance holes and head diameters, read 2026-11-07
- McFeely’s, Drilling chart for screw sizes (straight pilot drill, shank hole, head size), read 2026-11-07
- MISUMI USA, Wood screw pilot hole sizes chart (straight bit columns), read 2026-11-07
- Bob Vila, How to drill a pilot hole: pilot hole sizes for wood screws, read 2026-11-07
- WoodBin, Wood screw pilot holes (shank hole column), read 2026-11-07
- USDA Forest Products Laboratory, Wood Handbook (FPL-GTR-190), ch. 8 Fastenings: lead holes and Table 8–9 screw shank diameters (as republished by CED Engineering, course S03-019), read 2026-11-07