Wood Screw Pilot Hole Size Converter
Pick a wood screw or lag screw size and get a practical pilot hole drill bit for softwood or hardwood, plus clearance hole size, decimal inches, and millimeters.
Convert screw size to pilot hole size
Use the defaults for a #8 wood screw, or choose a common wood screw or lag screw size.
For a #8 wood screw in hardwood, start with a 7/64 inch pilot hole. Use about 11/64 inch for a clearance hole through the top board.
How to use the pilot hole conversion
- Choose whether you are using a regular wood screw or a heavier lag screw.
- Select the screw size shown on the box or plan.
- Use the softwood setting for pine, cedar, fir, plywood, and similar material.
- Use the hardwood setting for oak, maple, walnut, cherry, and dense boards that split more easily.
- Drill a test hole in scrap when the project is delicate, near an edge, or uses unusual screws.
Common wood screw pilot hole chart
| Screw | Softwood pilot | Hardwood pilot | Clearance |
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Wood screw pilot hole FAQ
What is the difference between softwood and hardwood pilot holes?
Softwood can usually accept a slightly smaller pilot hole because the fibers compress more easily. Hardwood normally needs a slightly larger pilot hole to reduce splitting and make driving easier.
When should I drill a clearance hole?
Use a clearance hole in the top piece when joining two boards. The larger hole lets the screw pull the top board tightly against the lower board instead of jacking the pieces apart.
Are these pilot hole sizes exact for every screw brand?
No. Thread shape, shank style, wood density, and moisture all matter. Treat these as practical starting sizes, then test on scrap for fine woodworking, edge work, or expensive material.