Wood Screw Sizes Chart: Gauge, Length & Pilot Hole Sizes
Wood screws are sized by two numbers — gauge (shank thickness, #4 to #14 for most projects) and length — never by thread pitch alone. Using the wrong gauge splits thin stock or strips out in MDF. This chart covers every common gauge’s diameter and pilot hole size for softwood and hardwood, plus how to pick length and head type.
Quick Answer
For most furniture and cabinets, use a #6 or #8 screw; for decking and framing, use #8 to #10. Drill a pilot hole close to the screw’s root diameter — roughly 65% of the shank diameter in softwood, 75% in hardwood — to prevent splitting. Let about two-thirds of the screw’s length bite into the base material.
Wood Screw Sizes Chart: Gauge, Diameter, Length & Pilot Hole
Each wood screw gauge has a fixed shank diameter set by ANSI/ASME B18.6.1. The chart below lists the six gauges used in almost all woodworking — #4 through #14 — with the diameter, the length range you’ll typically find in stores, and the pilot hole size for softwood versus hardwood.
| Gauge | Diameter (in / mm) | Common Lengths | Pilot Hole — Softwood | Pilot Hole — Hardwood |
|---|---|---|---|---|
| #4 | 0.112″ / 2.84mm | 3/8″ – 1″ | 1/16″ | 5/64″ |
| #6 | 0.138″ / 3.51mm | 3/8″ – 2″ | 3/32″ | 7/64″ |
| #8 | 0.164″ / 4.17mm | 3/4″ – 3″ | 7/64″ | 1/8″ |
| #10 | 0.190″ / 4.83mm | 1″ – 3-1/2″ | 1/8″ | 9/64″ |
| #12 | 0.216″ / 5.49mm | 1″ – 4″ | 9/64″ | 5/32″ |
| #14 | 0.242″ / 6.15mm | 1-1/2″ – 4″ | 11/64″ | 3/16″ |
Pilot hole sizing isn’t perfectly standardized across manufacturers — different fastener makers publish figures that vary by about one drill-bit increment. The sizes above use the common trade convention of roughly two-thirds of the shank diameter in softwood and three-quarters in hardwood; treat them as a reliable starting point and test on scrap first, especially near the edge of a board where splitting risk is highest.
📊 Wood screw shank diameter follows a fixed formula: D = 0.060 in. + (gauge × 0.013 in.), standardized under ANSI/ASME B18.6.1 — Source: Engineer’s Edge, ANSI B18.6.1
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Different Types Of Wood Screws
The type and size of screw you use affects the strength, stability, and appearance of your finished project. The three types below cover nearly every woodworking situation — traditional wood screws, chipboard screws, and deck screws. If you’re fastening into a fence rather than a bench or cabinet, see our fence screw guide for the coating and length specifics that apply outdoors.
Traditional Wood Screws
Traditional (slotted) wood screws are designed for softwoods, plywood, and other solid material. They have a sharp, pointed tip for easy penetration and a coarse thread for holding power, in sizes from #0 to #24 — larger numbers mean a thicker shank.
Chipboard Screws
Chipboard screws are built for particle board, MDF, and other composite wood. Deep threads and a sharp point let them grip the material without causing it to split, but you still need the correct pilot hole for the panel’s thickness to get a reliable hold.
Deck Screws
Deck screws are engineered for outdoor and high-moisture use — decking, fences, and other exterior projects. They’re made from corrosion-resistant stainless steel or coated carbon steel, with a sharp self-drilling point and coarse threads for easy installation and maximum holding power.
What Is A Wood Screw, Exactly?
A wood screw is a threaded fastener with a sharp, self-starting point that grips directly into wood fiber without a pre-tapped hole or nut. Its thread is coarser than a machine screw’s and usually runs only partway up the shank, leaving a smooth section below the head. Use a wood screw — not a machine screw or a bolt — any time you’re joining wood to wood or wood to a soft composite without threaded metal on the other side.
| Type | Best For | Typical Material | Drive |
|---|---|---|---|
| Traditional | Softwood, plywood, general joinery | Uncoated or zinc-plated steel | Slotted or Phillips |
| Chipboard | Particleboard, MDF, composite panels | Coated steel | Phillips or Pozi |
| Deck | Exterior, pressure-treated lumber | Stainless steel or coated carbon steel | Square or star (Torx) |
Wood Screw Anatomy
Knowing the parts of a wood screw helps you choose the right one and read a spec sheet correctly. The four major parts are the head, shank, threads, and point.
Understanding Major Parts
The head sits flush or proud of the surface and gives a tool something to drive against. The shank is the screw’s main body; the threads are the ridges that grip the wood. The point, usually sharp, starts the screw into the material.
Importance Of Thread Pitch And Diameter
Thread pitch (the distance between threads) and shank diameter both determine holding strength. A finer pitch grips better in dense hardwood; a coarser pitch grips better in softwood and composite panels. Larger diameters add stability and load-bearing capacity, which is why the gauge chart above matters more than length alone when strength is the concern.
Deciphering Wood Screw Sizes
Wood screw sizes are written as gauge, then length — for example, a #8 x 1-1/4″ screw is a #8 gauge screw that’s 1-1/4 inches long. Metric screws are labeled by shank diameter in millimeters instead of a gauge number.
Reading Screw Size Markings
Packaging typically lists gauge number, length in inches, and sometimes thread count. A box marked “#8 x 1-1/4″” tells you both numbers you need without measuring.
Metric Vs. Imperial Measurements
Imperial (gauge + inches) is standard in the US; metric (diameter in mm) is standard in Europe. The diameter column in the chart above converts between the two so you can match a metric screw to its closest US gauge.
| Measurement Type | Key Characteristics |
|---|---|
| Metric | Specified in millimeters; standard in European markets |
| Imperial | Measured by gauge number and inches; standard in the US |
- Always check the manufacturer’s spec sheet for the exact gauge and length — markings vary between brands.
- Match pilot hole size to material density, not just gauge (see the chart above).
Choosing The Right Wood Screw
Two factors decide the right screw: the thickness of the material you’re joining, and how much weight the joint needs to carry.
Considering Wood Thickness
Thin stock needs a shorter, thinner screw so the point doesn’t punch through the far side. Thicker stock needs a longer, thicker screw for a solid bond. As a rule of thumb, aim for the screw to penetrate about two-thirds of the way into the piece it’s anchoring into, and go up one gauge when moving from a softwood like pine to a hardwood like oak or maple.
Weight-bearing Capacities
A screw’s load capacity depends on its material, diameter, and how much thread is actually engaged in solid wood — not just its length. Undersized screws loosen over time under load; check the manufacturer’s spec sheet, or the chart above, before committing to a gauge for a load-bearing joint like a shelf bracket or stair tread.
Practical Applications
Securing Cabinets And Furniture
Smaller gauges like #6 or #8 suit lightweight furniture and cabinet face frames; #10 or #12 suit heavier pieces that need more shear strength at the joint. Match the drive and thread size so the connection doesn’t wobble loose over time.
Outdoor Construction Projects
For decks, sheds, and pergolas, use screws with a weather-resistant coating — stainless steel or hot-dip galvanized for lumber treated with modern ACQ preservatives, since standard zinc plating corrodes quickly against the copper in that treatment. A larger diameter and length also help hold pressure-treated or hardwood framing together through seasonal wood movement.
Tips And Tricks
Pre-drilling Pilot Holes
A pilot hole keeps the wood from splitting when you drive a screw. Use the chart above to match the bit to your gauge and wood type.
- Choose the pilot bit size from the softwood or hardwood column above.
- Drill to the same depth as the screw’s length.
- Keep the pilot hole straight so the screw doesn’t wander off-line.
Countersinking For A Professional Finish
Countersinking creates a conical recess so the screw head sits flush with, or just below, the surface.
- Use a countersink bit sized to your screw’s head, not just its gauge.
- Test the depth on scrap before committing to visible show-face material.
- Adjust the countersink depth per gauge — a #4 and a #12 need different settings.
Pilot hole and countersink depth aren’t the only variables — bit chuck alignment matters too, especially on a drill press where the bit has to enter dead-center on a narrow dowel or edge-grain piece.
For the pilot hole and countersink hardware to match your exact gauges from the chart above, see the drill bit sets in the comparison box below.
Related Screw & Drilling Guides
For the matching driver bit or tip size instead of the screw’s shank gauge, see our screwdriver size chart. If you’d rather look up a pilot hole size directly by drill bit rather than by gauge table, our dedicated pilot-hole drill size guide covers the same data from that angle. For cabinet-specific screw selection, see what screws to use for cabinets. All three sit under our full drilling and fastening hub.
Frequently Asked Questions Of Wood Screws Sizes Chart
What Are The Different Wood Screw Sizes Available?
Wood screws are available in gauges from #0 up to #24, though #4 through #14 cover nearly every woodworking project. The gauge number sets the shank diameter; length is specified separately and typically ranges from 3/8 inch to 4 inches or more, depending on the gauge and application.
How Do I Determine The Right Wood Screw Size For My Project?
Match the gauge to the load the joint carries and the length so roughly two-thirds of the screw penetrates the base material. A #6 or #8 covers most furniture and cabinet work; #10 or #12 suits decking, framing, and heavier joints. Check the chart above for exact diameters and pilot hole sizes.
Can I Use Any Type Of Wood Screw For Any Project?
No. Traditional wood screws suit softwood and plywood, chipboard screws suit particleboard and MDF, and deck screws suit exterior and pressure-treated lumber. Using an uncoated traditional screw outdoors, for example, invites rust and joint failure within a season or two.
What Is The Difference Between Flat Head And Countersunk Wood Screws?
Flat head and countersunk describe the same head shape in most catalogs — a tapered underside that sinks into a matching countersunk hole so the top sits flush with the wood surface. A round or pan head, by contrast, stays proud of the surface and is not meant to be recessed.
What Size Drill Bit Do I Need For A #8 Wood Screw?
For a #8 wood screw (0.164 in. shank), drill a 7/64 in. pilot hole in softwood or a 1/8 in. pilot hole in hardwood. That’s roughly 65–75% of the screw’s shank diameter, which lets the threads bite without splitting the wood. See the chart above for other gauges.
Is A Bigger Wood Screw Gauge Always Stronger?
Not always. A higher gauge means a thicker shank and more shear strength, but only if the material can take the larger pilot hole a thicker screw needs — an oversized screw near the edge of thin stock or MDF can split the piece instead of adding strength. Match gauge to material thickness first, then maximize gauge within that limit.
Conclusion
Gauge sets the shank diameter, length sets how deep the screw bites, and the pilot hole keeps the wood from splitting while it does. Bookmark the chart above and match gauge to material density before you reach for a driver — it’s the single step that prevents most stripped or split joints.
