Pilot Hole & Screw Size Calculator
Almost every pilot hole chart in circulation prints one number per screw gauge, as if pine and white oak were the same material. They are not: the same hole that grips softwood splits a dense hardwood the moment the shank passes the threads. Pick your gauge and the board that is taking the threads, and this scales the pilot, the clearance hole and the safe distances by the density of the wood in front of you.
Gauge, not length. Major diameter is 0.060in plus 0.013in per number.
The piece taking the threads, not the piece being clamped down.
Used to work out the shortest screw that still holds.
Pilot hole
1/8″
0.119in · 3.0 mm
Clearance hole
3/16″
Top piece, full depth
Counterbore
21/64″
Plug or washer head
- Split risk
- High
- Pilot as a share of shank
- 73%
- Minimum distance from the end
- 1.15in
- Minimum distance from an edge
- 0.41in
- Thread engagement needed
- 1.00in
- Shortest screw that works
- 1.75in
A pilot that is right for pine splits red oak. This hole is scaled by specific gravity — 0.66 here — so it lands at 73% of the shank instead of one number for every board. Thread root diameter on a standard wood screw is about 0.115in, so anything at or a whisker under that still bites.
| Gauge | Shank | Pilot | Clearance | Counterbore |
|---|---|---|---|---|
| #4 | 0.112in | 5/64″ | 1/8″ | 15/64″ |
| #5 | 0.125in | 3/32″ | 9/64″ | 1/4″ |
| #6 | 0.138in | 3/32″ | 5/32″ | 9/32″ |
| #7 | 0.151in | 7/64″ | 11/64″ | 5/16″ |
| #8 | 0.164in | 1/8″ | 3/16″ | 21/64″ |
| #9 | 0.177in | 1/8″ | 3/16″ | 23/64″ |
| #10 | 0.190in | 9/64″ | 13/64″ | 25/64″ |
| #12 | 0.216in | 5/32″ | 15/64″ | 7/16″ |
| #14 | 0.242in | 11/64″ | 17/64″ | 31/64″ |
Print the table, tape it inside the cabinet door, and stop guessing. The rest of the shop numbers are in our calculator library.