What size pilot hole do I drill for wood screws?

For softwood, drill a pilot hole 1/64 inch smaller than the screw shank diameter. For hardwood, drill the same diameter as the shank. For example, a #8 screw (0.164 inch shank) needs a 5/32 inch pilot in softwood and an 11/64 inch pilot in hardwood. Near board ends, size up slightly to prevent splitting. Many manufacturers publish pilot hole charts for their specific screw lines.

What does the screw gauge number mean?

The gauge number indicates the screw's shank diameter. Higher numbers mean larger diameter: #6 is 0.138 inch, #8 is 0.164 inch, #10 is 0.190 inch, #12 is 0.216 inch. The gauge does not indicate length. A complete screw designation includes both gauge and length, such as #8 x 1-1/4 inch. Gauge determines the holding strength and the pilot hole size needed.

When should I use coarse thread vs fine thread screws?

Coarse thread screws are designed for softwoods (pine, cedar, fir) and sheet materials like plywood and MDF — the wide thread spacing grabs well in softer fibers. Fine thread screws are for hardwoods (oak, maple, walnut) where the denser grain holds the tighter thread pattern better. Using coarse threads in hardwood can cause splitting, while fine threads in softwood provide less holding power.

Wood Screw Size Chart and Guide | Lumberama

Fasteners

Wood Screw Size Chart and Selection Guide (2026)

Prepared by Lumberama's Hardware & Accessories Team

|Last updated June 13, 2026|Sources & methodology

Understanding wood screw sizing eliminates guesswork and ensures strong, clean joints in every woodworking and construction project. Screw gauge numbers, length designations, head types, and thread patterns all affect performance. This guide provides a comprehensive size chart and explains how to select the right screw for your wood species, joint type, and application.

Key Takeaways

Understanding wood screw sizing eliminates guesswork and ensures strong, clean joints in every woodworking and construction project.
Screw gauge numbers, length designations, head types, and thread patterns all affect performance.
This guide provides a comprehensive size chart and explains how to select the right screw for your wood species, joint type, and application.
Screw gauge (diameter from #4 to #14), length for the materials being joined, head type (flat, round, pan, or washer-head), drive type (Phillips, square, star/Torx), thread type (coarse for softwood, fine for hardwood), material (steel, stainless, brass, silicon bronze), and whether you need a pilot hole for your wood species.
GRK Multi-Purpose screws combine aggressive threads, self-countersinking heads, and star drive for versatility across applications.

What to Consider

Screw gauge (diameter from #4 to #14), length for the materials being joined, head type (flat, round, pan, or washer-head), drive type (Phillips, square, star/Torx), thread type (coarse for softwood, fine for hardwood), material (steel, stainless, brass, silicon bronze), and whether you need a pilot hole for your wood species.

Product Comparison

GRK Multi-Purpose screws combine aggressive threads, self-countersinking heads, and star drive for versatility across applications. SPAX multi-material screws feature a patented serrated thread that reduces splitting. Kreg pocket-hole screws are purpose-built for pocket-hole joinery with specific thread and head profiles. McFeely's offers the widest selection of specialty wood screws including square-drive and stainless options in every gauge and length.

Size Selection Guide

General rule: screw length should be 2-3 times the thickness of the top piece. #6 screws for trim and small projects (shank: 0.138 inch). #8 screws for general woodworking and cabinets (shank: 0.164 inch). #10 screws for structural and outdoor use (shank: 0.190 inch). #12 and #14 for heavy-duty applications. Pilot hole: drill 1/64 inch smaller than shank diameter in softwood, exact shank diameter in hardwood. Countersink for flat-head screws.

Installation Tips

Always predrill when screwing within 2 inches of a board edge or end. Match your pilot hole bit to the screw gauge using a chart or by holding the bit behind the screw — the bit should be visible through the threads but hidden by the shank. Use a countersink for flat-head screws to sit flush. Drive screws with a drill or impact driver set to the appropriate torque. Star/Torx drive resists cam-out better than Phillips.

Common Mistakes to Avoid

Using screws that are too short for adequate holding power in the bottom piece. Skipping pilot holes in hardwood causing splits. Using Phillips drive where star/Torx would prevent cam-out. Not matching the screw gauge to the material thickness. Confusing thread count with gauge number. Using brass screws to drive into hardwood (brass is too soft — drive a steel screw first as a pilot, then replace with brass).

Budget Guide

Standard steel wood screws cost $5-10 per pound (approximately 100-200 screws depending on size). Premium coated and star-drive screws run $8-15 per pound. Stainless steel screws cost $15-30 per pound. Brass and silicon bronze screws are $20-40 per pound. Pocket-hole screws run $10-18 per box of 250-500. An assorted screw kit for a home workshop costs $25-50.