Wood Screw Specifications
Complete sizing charts, pilot hole guides, and specifications for US and metric wood screws - from basic construction to deck and specialty applications
Downloadable Reference Guides
Quick access to all wood screw specification charts and guides
US Wood Screw Sizes
Wood screws are designed specifically for fastening into wood with tapered shafts and coarse threads. US sizes range from #2 (smallest commonly used) to 5/16" diameter, with various lengths available for each size.
| Gauge Size | Shank Diameter | Root Diameter | Threads Per Inch | Common Lengths |
|---|---|---|---|---|
| #2 | 0.086" (2.18mm) | 0.062" | 56 | 1/4" - 1" |
| #3 | 0.099" (2.51mm) | 0.073" | 48 | 1/4" - 1-1/4" |
| #4 | 0.112" (2.84mm) | 0.084" | 42 | 1/4" - 1-1/2" |
| #5 | 0.125" (3.18mm) | 0.095" | 38 | 3/8" - 2" |
| #6 | 0.138" (3.51mm) | 0.106" | 32 | 3/8" - 3" |
| #7 | 0.151" (3.84mm) | 0.120" | 30 | 1/2" - 3" |
| #8 | 0.164" (4.17mm) | 0.131" | 32 | 1/2" - 3-1/2" |
| #9 | 0.177" (4.50mm) | 0.145" | 30 | 5/8" - 4" |
| #10 | 0.190" (4.83mm) | 0.158" | 24 | 5/8" - 5" |
| #12 | 0.216" (5.49mm) | 0.182" | 24 | 3/4" - 5" |
| #14 | 0.242" (6.15mm) | 0.207" | 20 | 3/4" - 6" |
| 1/4" | 0.250" (6.35mm) | 0.211" | 20 | 1" - 6" |
| 5/16" | 0.3125" (7.94mm) | 0.265" | 18 | 1-1/2" - 6" |
Understanding Wood Screw Sizing
- Gauge Number: Indicates the shank diameter (#2 is smallest, larger numbers = larger diameter)
- Length: Always measured from the point where the screw sits flush with the wood surface
- Shank Diameter: The unthreaded portion under the head
- Root Diameter: The smallest diameter at the bottom of the threads
- Tapered Design: Wood screws have a gradually decreasing diameter to prevent wood splitting
Download US Wood Screw Chart
Print this chart for easy reference in your workshop
Pilot Hole Drilling Guide
Proper pilot holes prevent wood splitting, ensure straight installation, and make driving screws easier. The correct pilot hole size depends on both the screw size and the wood hardness.
| Screw Size | Softwood Pilot Hole |
Hardwood Pilot Hole |
Countersink Diameter |
Clearance Hole |
|---|---|---|---|---|
| #2 | 1/16" (1.5mm) | 5/64" (2.0mm) | 3/32" | 3/32" |
| #3 | 1/16" (1.5mm) | 5/64" (2.0mm) | 7/64" | 7/64" |
| #4 | 5/64" (2.0mm) | 3/32" (2.4mm) | 1/8" | 1/8" |
| #5 | 5/64" (2.0mm) | 3/32" (2.4mm) | 9/64" | 9/64" |
| #6 | 3/32" (2.4mm) | 7/64" (2.8mm) | 5/32" | 9/64" |
| #7 | 3/32" (2.4mm) | 7/64" (2.8mm) | 5/32" | 5/32" |
| #8 | 7/64" (2.8mm) | 1/8" (3.2mm) | 11/64" | 11/64" |
| #9 | 7/64" (2.8mm) | 1/8" (3.2mm) | 3/16" | 3/16" |
| #10 | 1/8" (3.2mm) | 9/64" (3.6mm) | 3/16" | 3/16" |
| #12 | 9/64" (3.6mm) | 5/32" (4.0mm) | 7/32" | 7/32" |
| #14 | 5/32" (4.0mm) | 3/16" (4.8mm) | 1/4" | 1/4" |
| 1/4" | 11/64" (4.4mm) | 3/16" (4.8mm) | 17/64" | 17/64" |
| 5/16" | 7/32" (5.5mm) | 15/64" (6.0mm) | 21/64" | 21/64" |
Softwoods Include:
- Pine (white, yellow, sugar)
- Cedar (red, white)
- Fir (Douglas fir)
- Spruce
- Redwood
- Hemlock
Hardwoods Include:
- Oak (red, white)
- Maple
- Cherry
- Walnut
- Ash
- Hickory
Pilot Hole Best Practices
- Depth: Drill pilot holes slightly shorter than the screw length
- Angle: Keep drill bit perfectly perpendicular to prevent angled screw installation
- Clearance Holes: Use in top piece when joining two boards to prevent wood separation
- Countersinking: Required for flathead screws to sit flush with the surface
- Hard vs. Soft: When in doubt about wood hardness, start with the smaller (softwood) pilot hole
Download Pilot Hole Guide
Print this essential reference for all your woodworking projects
Types of Wood Screws
Different wood screw designs are optimized for specific applications. Choosing the right type ensures strong connections and professional results.
Traditional Wood Screws
Features: Tapered shank, gimlet point, coarse threads
- Classic design for general woodworking
- Partial threading (2/3 of length)
- Requires pilot holes
- Available in slotted or Phillips
- Best for: Furniture, cabinets, fine woodworking
- Materials: Steel, brass, bronze, stainless
Deck Screws
Features: Fully threaded, bugle head, corrosion resistant
- Designed for outdoor applications
- Self-countersinking bugle head
- Sharp point for self-starting
- ACQ/CA compatible coatings
- Best for: Deck boards, outdoor structures, pressure-treated lumber
- Materials: Coated steel, stainless steel
Construction Screws
Features: High-low thread design, type 17 point
- Extra strong for structural applications
- Dual thread pattern for faster driving
- Type 17 auger point (no pilot hole)
- Star/square drive for high torque
- Best for: Framing, subfloors, sheathing, structural connections
- Materials: Heat-treated steel
Drywall Screws
Features: Bugle head, fine threads, sharp point
- Designed for gypsum board attachment
- Self-countersinking head
- Fine threads prevent paper tearing
- Black phosphate coating
- Best for: Drywall to wood or metal studs
- Materials: Hardened steel
Pocket Hole Screws
Features: Flat underside head, coarse threads, blunt tip
- Specialized for pocket hole joinery
- Washer head design prevents splitting
- Self-tapping tip
- Square drive standard
- Best for: Face frames, cabinet assembly, joinery
- Materials: Case-hardened steel
Trim Head Screws
Features: Small diameter head, fine threads
- Minimal head visibility
- Head can be filled and painted
- Fine threads for hardwoods
- Sharp point
- Best for: Trim, molding, finish carpentry
- Materials: Coated steel, stainless
Lag Screws (Lag Bolts)
Features: Hex head, large diameter, wood threads
- Heavy-duty fastening
- Driven with wrench or socket
- Requires pilot hole
- Very high holding power
- Best for: Heavy timber, structural connections, posts to beams
- Materials: Steel, hot-dipped galvanized
Particleboard Screws
Features: Double-lead threads, thin shank
- Optimized for engineered wood
- Prevents material breakout
- Wide thread spacing
- Self-tapping
- Best for: MDF, particleboard, melamine, chipboard
- Materials: Hardened steel
Download Wood Screw Types Comparison
Print this guide to choose the right screw for every project
Wood Screw Head Styles
The head style affects both appearance and functionality. Choose based on whether you need flush, countersunk, or raised installation.
Flat Head (Countersunk)
Profile: Conical underside, flat top
- Sits flush when countersunk
- 82° standard angle
- Clean, finished appearance
- Most common for traditional wood screws
- Best for: Hinges, hardware mounting, general woodworking
Pan Head
Profile: Rounded top with flat bearing surface
- Low profile design
- Large bearing surface
- Does not require countersinking
- Good load distribution
- Best for: Sheet goods, metal-to-wood applications
Round Head
Profile: Dome-shaped top
- Traditional decorative appearance
- Highly visible when installed
- Strong bearing surface
- Often used with finishing washers
- Best for: Visible fastening, decorative applications
Oval Head
Profile: Countersunk with rounded top
- Combination of flat and round
- Partially visible above surface
- Decorative appearance
- Requires countersinking
- Best for: Furniture, cabinets, finish work
Bugle Head
Profile: Curved taper, flat or slightly domed top
- Self-countersinking design
- Prevents material crushing
- No pre-countersinking needed
- Standard on deck and drywall screws
- Best for: Decking, drywall, construction
Truss Head
Profile: Extra-wide, low dome
- Very large bearing surface
- Prevents pull-through
- Low profile
- Good for soft materials
- Best for: Sheet metal to wood, thin materials
Hex Head
Profile: Hexagonal head for wrench driving
- Driven with socket or wrench
- Very high torque capacity
- Used on lag screws
- Washer face or plain
- Best for: Heavy-duty structural connections
Trim Head
Profile: Small diameter countersunk head
- Minimally visible
- Can be filled and painted
- Smaller than standard flathead
- Less holding power in head
- Best for: Finish carpentry, molding, trim
Washer Head
Profile: Built-in washer under flathead
- Integrated washer design
- Extra bearing surface
- Prevents pull-through
- Used on pocket hole screws
- Best for: Pocket holes, soft materials
Download Wood Screw Head Styles Guide
Print this guide to identify and choose the best wood screw head styles for your application.
Drive Types for Wood Screws
Phillips Drive
- Most common on traditional wood screws
- Self-centering design
- Available in #1, #2, #3 sizes
- Pros: Universal, widely available
- Cons: Can cam-out under high torque
Square Drive (Robertson)
- Common on deck and construction screws
- Excellent torque transfer
- Bit stays in screw
- Pros: No cam-out, one-handed driving
- Cons: Less common in US
Star Drive (Torx)
- Increasingly popular for wood screws
- Superior torque transfer
- No cam-out
- Pros: High torque, long bit life
- Cons: Requires Torx bits
Slotted Drive
- Traditional wood screw drive
- Simple single slot
- Common on brass and decorative screws
- Pros: Classic appearance
- Cons: Easily damaged, hard to drive
Combo Drive (Phillips/Square)
- Accepts both Phillips and square bits
- Versatile option
- Common on pocket hole screws
- Pros: Maximum compatibility
- Cons: Neither drive fits perfectly
Hex Socket
- Used on structural and lag screws
- High torque capacity
- Requires hex key or bit
- Pros: Very strong, no stripping
- Cons: Limited to larger screws
Materials & Coatings
Wood screw materials and coatings determine strength, corrosion resistance, and suitability for different environments.
Steel (Uncoated)
- Use: Interior applications only
- Finish: Bright steel (shiny)
- Pros: Inexpensive, strong
- Cons: Rusts easily when exposed to moisture
- Best for: Indoor furniture, interior framing
Zinc Plated Steel
- Use: Light-duty outdoor, general purpose
- Finish: Silver/gray appearance
- Pros: Good corrosion resistance, affordable
- Cons: Not for marine or treated lumber
- Best for: General construction, sheltered outdoor
Yellow Zinc (Gold) Coated
- Use: Moderate outdoor exposure
- Finish: Golden/yellow appearance
- Pros: Better corrosion resistance than zinc
- Cons: Still not for marine environments
- Best for: Deck screws, outdoor projects
ACQ/CA Compatible Coatings
- Use: Pressure-treated lumber
- Finish: Various (green, tan, gray)
- Pros: Resists chemical corrosion from treated wood
- Cons: More expensive
- Best for: Decks, outdoor structures with PT lumber
Stainless Steel (304/316)
- Use: Marine, high-corrosion environments
- Finish: Bright metallic
- Pros: Excellent corrosion resistance, strong
- Cons: Most expensive option
- Best for: Marine applications, coastal areas, treated lumber
Brass/Bronze
- Use: Decorative, marine applications
- Finish: Gold/bronze color
- Pros: Corrosion resistant, attractive
- Cons: Softer, more expensive, can break easily
- Best for: Hardware mounting, marine, visible locations
Important: Treated Lumber Compatibility
- Standard zinc screws will corrode rapidly in ACQ/CA pressure-treated lumber
- Use ACQ-compatible coated screws or stainless steel for treated wood
- Corrosion can cause structural failure and staining
- Check local building codes for required fastener types
Applications & Installation Best Practices
Choosing the Right Length
General Rule: Screw length should penetrate 2/3 into the base material
Example: For 3/4" thick boards being fastened together:
- Top board: 3/4"
- Bottom board penetration needed: approximately 1" (2/3 of 3/4" × 2)
- Recommended screw length: 1-3/4" to 2"
Installation Tips
Preventing Wood Splitting
- Always drill pilot holes near board ends
- Use slightly smaller pilot holes for softwoods
- Keep screws at least 3/4" from edges
- Stagger screws in parallel rows
- Consider pre-drilling in hardwoods
Proper Driving Technique
- Use correct bit size for drive type
- Maintain steady pressure
- Drive perpendicular to surface
- Stop when head is flush (don't overdrive)
- Use clutch setting on power drills
Maximum Holding Power
- Ensure adequate thread engagement
- Use washers for large loads
- Avoid overtightening
- Check wood moisture content
- Allow treated lumber to dry before fastening
Common Applications
Deck Construction
- Use ACQ-compatible or stainless deck screws
- #8 or #10 screws for decking boards
- 2-1/2" to 3" length for 5/4 decking
- Two screws per joist for each board
- Structural screws for joist hangers and framing
Cabinet & Furniture Assembly
- Pocket hole screws for face frames
- #6 to #8 for general assembly
- Particleboard screws for MDF/melamine
- Pre-drill all hardwood joints
- Use brass for visible hardware mounting
Outdoor Projects
- Use corrosion-resistant coatings
- Match screw coating to lumber treatment
- Larger screws (#10-#12) for structural connections
- Pre-drill all connections in pressure-treated lumber
- Consider stainless in coastal areas
Trim & Finish Work
- Use trim head screws to minimize visibility
- #6 or #7 screws for most trim
- Pre-drill hardwood trim
- Countersink and fill screw holes
- Match screw length to substrate depth
Safety & Building Codes
- Always follow local building codes for structural applications
- Use approved fasteners for decks and load-bearing structures
- Wear safety glasses when driving screws
- Never use drywall screws for structural connections
- Inspect wood for knots, cracks, or defects before fastening
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