Pilot hole size chart
Pilot and clearance drills for every wood screw gauge, in hardwood and in softwood. The clearance column is the one people skip, and it is the reason a screwed joint sits with a gap in it.
| Gauge | Pilot — hardwood | Pilot — softwood | Clearance (top piece) |
|---|---|---|---|
| #2 | 3/64" | 1/32" | 3/32" |
| #3 | 1/16" | 3/64" | 7/64" |
| #4 | 1/16" | 3/64" | 7/64" |
| #5 | 5/64" | 1/16" | 1/8" |
| #6 | 5/64" | 1/16" | 9/64" |
| #7 | 3/32" | 1/16" | 5/32" |
| #8 | 3/32" | 5/64" | 11/64" |
| #9 | 7/64" | 5/64" | 3/16" |
| #10 | 7/64" | 3/32" | 3/16" |
| #12 | 1/8" | 3/32" | 7/32" |
| #14 | 9/64" | 7/64" | 1/4" |
Reading it
- The pilot is sized to the screw's root, so the threads still have wood to cut. The clearance hole is sized to the outside of the thread, so the top piece hangs on the head rather than on the threads.
- Hardwood takes the larger pilot. Dense wood splits where softwood would compress.
- Near an end or an edge, go up a size and wax the threads. End grain splits with very little provocation.
For the case this table does not cover
- Pilot hole calculator
The right drill bit for a wood screw, by gauge number and by softwood or hardwood.
- Pocket hole screw calculator
Screw length and thread by material thickness, and how far apart to space the holes along an edge joint.