Wood Screw Pilot Hole Chart
Photo via Unsplash
Complete reference guide for pilot hole, clearance hole, and countersink sizes for all common wood screw gauges and types.
Photo via Unsplash
Complete reference guide for pilot hole, clearance hole, and countersink sizes for all common wood screw gauges and types.
Using the correct pilot hole size prevents wood from splitting, ensures screws drive straight, and creates the strongest possible joint. This comprehensive chart covers standard wood screws, deck screws, pocket hole screws, lag bolts, and specialty fasteners.
This chart shows pilot hole sizes for standard wood screws. The softwood column is for pine, cedar, fir, and similar species. The hardwood column is for oak, maple, walnut, and other dense woods.
| Screw Gauge | Screw Diameter | Pilot Hole (Softwood) | Pilot Hole (Hardwood) | Clearance Hole (Shank) | Countersink Diameter |
|---|---|---|---|---|---|
| #2 | 0.086" (2.2mm) | 1/16" (1.6mm) | 1/16" (1.6mm) | 3/32" (2.4mm) | 3/16" (4.8mm) |
| #3 | 0.099" (2.5mm) | 1/16" (1.6mm) | 5/64" (2.0mm) | 7/64" (2.8mm) | 7/32" (5.6mm) |
| #4 | 0.112" (2.8mm) | 1/16" (1.6mm) | 5/64" (2.0mm) | 1/8" (3.2mm) | 1/4" (6.4mm) |
| #5 | 0.125" (3.2mm) | 5/64" (2.0mm) | 3/32" (2.4mm) | 9/64" (3.6mm) | 1/4" (6.4mm) |
| #6 | 0.138" (3.5mm) | 5/64" (2.0mm) | 3/32" (2.4mm) | 9/64" (3.6mm) | 9/32" (7.1mm) |
| #7 | 0.151" (3.8mm) | 3/32" (2.4mm) | 7/64" (2.8mm) | 5/32" (4.0mm) | 5/16" (8mm) |
| #8 | 0.164" (4.2mm) | 7/64" (2.8mm) | 1/8" (3.2mm) | 11/64" (4.4mm) | 5/16" (8mm) |
| #9 | 0.177" (4.5mm) | 7/64" (2.8mm) | 1/8" (3.2mm) | 3/16" (4.8mm) | 3/8" (9.5mm) |
| #10 | 0.190" (4.8mm) | 1/8" (3.2mm) | 9/64" (3.6mm) | 3/16" (4.8mm) | 3/8" (9.5mm) |
| #12 | 0.216" (5.5mm) | 9/64" (3.6mm) | 5/32" (4.0mm) | 7/32" (5.6mm) | 7/16" (11mm) |
| #14 | 0.242" (6.1mm) | 5/32" (4.0mm) | 11/64" (4.4mm) | 1/4" (6.4mm) | 1/2" (12.7mm) |
Sheet metal screws have sharper threads designed to cut into thin metal. When used in wood, use the softwood pilot hole size.
| Screw Size | Screw Diameter | Pilot Hole (Thin Metal) | Pilot Hole (Thick Metal) | Pilot Hole (Wood) |
|---|---|---|---|---|
| #4 | 0.112" (2.8mm) | 3/32" (2.4mm) | 7/64" (2.8mm) | 1/16" (1.6mm) |
| #6 | 0.138" (3.5mm) | 7/64" (2.8mm) | 1/8" (3.2mm) | 5/64" (2.0mm) |
| #8 | 0.164" (4.2mm) | 1/8" (3.2mm) | 9/64" (3.6mm) | 7/64" (2.8mm) |
| #10 | 0.190" (4.8mm) | 9/64" (3.6mm) | 5/32" (4.0mm) | 1/8" (3.2mm) |
| #12 | 0.216" (5.5mm) | 11/64" (4.4mm) | 3/16" (4.8mm) | 9/64" (3.6mm) |
| #14 | 0.242" (6.1mm) | 3/16" (4.8mm) | 13/64" (5.2mm) | 5/32" (4.0mm) |
Deck screws are designed for exterior use with coarse threads. Most have a self-drilling tip, but pilot holes are still recommended for hardwoods and near edges.
| Screw Size | Screw Diameter | Pilot Hole (Softwood/PT Lumber) | Pilot Hole (Hardwood Decking) | Clearance Hole |
|---|---|---|---|---|
| #7 (2") | 0.151" (3.8mm) | 3/32" (2.4mm) | 7/64" (2.8mm) | 5/32" (4.0mm) |
| #8 (2-1/2") | 0.164" (4.2mm) | 7/64" (2.8mm) | 1/8" (3.2mm) | 11/64" (4.4mm) |
| #9 (3") | 0.177" (4.5mm) | 7/64" (2.8mm) | 1/8" (3.2mm) | 3/16" (4.8mm) |
| #10 (3-1/2") | 0.190" (4.8mm) | 1/8" (3.2mm) | 9/64" (3.6mm) | 3/16" (4.8mm) |
| #12 (4") | 0.216" (5.5mm) | 9/64" (3.6mm) | 5/32" (4.0mm) | 7/32" (5.6mm) |
Pocket hole screws (like Kreg screws) are designed for pocket hole joinery. The pocket hole jig creates the angled hole, but you may need pilot holes in the receiving piece for hardwoods.
| Material Thickness | Screw Length | Screw Type | Pilot Hole (Hardwood Only) | Drill Bit Size |
|---|---|---|---|---|
| 1/2" | 3/4" | Fine Thread | 5/64" (2.0mm) | 3/8" step drill |
| 3/4" | 1-1/4" | Coarse/Fine | 5/64" (2.0mm) | 3/8" step drill |
| 1" | 1-1/2" | Coarse/Fine | 3/32" (2.4mm) | 3/8" step drill |
| 1-1/4" | 2" | Coarse/Fine | 3/32" (2.4mm) | 3/8" step drill |
| 1-1/2" | 2-1/2" | Coarse/Fine | 7/64" (2.8mm) | 3/8" step drill |
Use coarse-thread pocket screws for softwoods and plywood. Use fine-thread screws for hardwoods and MDF. Pilot holes in the receiving piece are typically only needed for dense hardwoods like oak, maple, or walnut.
Lag screws (lag bolts) require two-stage drilling: a pilot hole for the threaded portion and a clearance hole for the unthreaded shank.
| Lag Screw Diameter | Pilot Hole (Softwood) | Pilot Hole (Hardwood) | Clearance Hole (Shank) | Counterbore (Washer) |
|---|---|---|---|---|
| 1/4" | 5/32" (4.0mm) | 3/16" (4.8mm) | 1/4" (6.4mm) | 5/8" (16mm) |
| 5/16" | 3/16" (4.8mm) | 7/32" (5.6mm) | 5/16" (8mm) | 3/4" (19mm) |
| 3/8" | 1/4" (6.4mm) | 5/16" (8mm) | 3/8" (9.5mm) | 7/8" (22mm) |
| 7/16" | 5/16" (8mm) | 3/8" (9.5mm) | 7/16" (11mm) | 1" (25mm) |
| 1/2" | 3/8" (9.5mm) | 7/16" (11mm) | 1/2" (12.7mm) | 1-1/8" (29mm) |
| 5/8" | 1/2" (12.7mm) | 9/16" (14mm) | 5/8" (16mm) | 1-3/8" (35mm) |
| 3/4" | 5/8" (16mm) | 11/16" (17mm) | 3/4" (19mm) | 1-1/2" (38mm) |
Traditional wood screws with tapered shanks. The pilot hole should be drilled to full screw depth. These screws typically have slotted or Phillips heads.
| Gauge | Root Diameter | Pilot (Softwood) | Pilot (Hardwood) | Notes |
|---|---|---|---|---|
| #6 | 0.091" | 5/64" | 3/32" | Common for light-duty work |
| #8 | 0.108" | 7/64" | 1/8" | Most popular size for furniture |
| #10 | 0.128" | 1/8" | 9/64" | Good for cabinetry and trim |
| #12 | 0.148" | 9/64" | 5/32" | Heavy-duty applications |
Self-drilling screws have a drill-point tip that eliminates the need for pilot holes in most softwoods and thin materials. However, pilot holes are still recommended for hardwoods and near edges.
| Screw Size | When to Use Pilot Hole | Pilot Size (if needed) | Typical Applications |
|---|---|---|---|
| #6 | Hardwood, near edges | 1/16" - 5/64" | Light construction, trim |
| #8 | Hardwood, near edges, dense PT lumber | 5/64" - 3/32" | General construction, decking |
| #10 | Hardwood, near edges, structural | 3/32" - 7/64" | Framing, heavy construction |
| #12 | Almost always recommended | 7/64" - 1/8" | Heavy structural work |
Premium structural screws like GRK, Spax, and TimberLok feature aggressive threads, self-drilling tips, and special coatings. They are engineered to be driven without pilot holes in most applications.
| Screw Diameter | Pilot Hole Needed? | Pilot Size (if used) | Best Practices |
|---|---|---|---|
| 0.151" (#7) | Rarely - only dense hardwoods | 3/32" | Drive at medium-high speed |
| 0.164" (#8) | Rarely - hardwoods, near edges | 7/64" | Let screw do the work |
| 0.190" (#10) | Sometimes - hardwoods, thin stock | 1/8" | Back off if resistance increases |
| 5/16" | Recommended for hardwoods | 3/16" | Use in structural applications |
| 3/8" | Recommended in most cases | 1/4" | Heavy timber connections |
GRK, Spax, and similar structural screws have special thread designs that cut fibers rather than displacing them. This reduces splitting but still benefits from pilot holes in very dense materials like white oak, ipe, or exotic hardwoods.
| Application | Pilot Hole Depth | Notes |
|---|---|---|
| Softwood - standard screws | 1/2 to 2/3 of screw length | Deeper if near edges |
| Hardwood - standard screws | Full thread length | Match screw thread depth |
| Lag screws | Full thread length | Plus clearance hole for shank |
| Edge screwing | Full screw length | Prevents splitting at end |
| End grain | Full screw length | Slightly larger diameter too |
Use our Drill and Tap Size Calculator for machine threads, including SAE, metric, and NPT pipe threads.
Open Drill & Tap CalculatorHaving the right drill bits on hand makes pilot hole drilling fast and accurate. These sets cover the full range of sizes in the charts above.
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For a #8 wood screw, use a 7/64" (2.8mm) pilot hole in softwood or a 1/8" (3.2mm) pilot hole in hardwood. The clearance hole (shank hole) should be 11/64" (4.4mm), and the countersink diameter is 5/16" (8mm). The #8 gauge is the most common size for furniture and cabinetry projects.
Not always. Pilot holes are essential for hardwoods to prevent splitting and for screws near edges or ends of boards. In softwood like pine or cedar, smaller screws (#6 and under) often don't need pilot holes if driven away from edges. Self-drilling and structural screws like GRK or Spax are specifically designed to be driven without pilot holes in most softwood applications, though pilot holes still help in hardwoods.
A pilot hole is drilled in the piece receiving the screw threads and is smaller than the screw diameter to allow the threads to bite and grip. A clearance hole (also called a shank hole or body hole) is drilled in the top piece and is larger than the screw shank, allowing the screw to pass through freely. This setup lets the screw pull the two pieces tightly together rather than just threading through both. For the strongest joints, use both a pilot hole and clearance hole.
Hardwoods like oak and maple are denser and more prone to splitting because their fibers resist displacement. Larger pilot holes remove more material, reducing the stress on wood fibers when the screw is driven. Softwoods like pine and cedar are more forgiving - their fibers compress around the screw threads, allowing smaller pilot holes for better grip. Using a softwood-sized pilot in hardwood risks splitting, while using hardwood-sized pilots in softwood may result in less holding power.