Plywood Calculator
Calculate how many sheets of plywood or OSB you need for subfloor, wall sheathing, or roof sheathing. Includes waste factor and layout visualization.
Application
Area Dimensions
Total Sheets
13 (4x8)
Sheet Layout Pattern
13 sheets × $38/sheet
- Stagger joints by at least 4' between rows for maximum strength
- Leave 1/8" gap between sheets for expansion
- Use 8d ring-shank nails at 6" on edges, 12" in field for subfloor
- Mark joist/rafter locations on sheets before installation
- Store sheets flat and keep dry until installation
Related Calculators
About This Calculator
The Plywood Calculator determines exactly how many sheets of plywood or OSB you need for subfloors, wall sheathing, roof sheathing, or any panel project—with optimized layout patterns to minimize waste and cutting. Whether you're installing 3/4" T&G subfloor over floor joists, 7/16" OSB wall sheathing, or 1/2" roof decking, accurate sheet estimation prevents costly over-ordering and frustrating material shortages.
Plywood and OSB (oriented strand board) are sold in standard 4×8, 4×10, and 4×12 foot sheets, but not all of that coverage translates to your finished project. Different applications have different waste factors—roof sheathing on hip roofs can waste 15-20% in angled cuts, while simple rectangular subfloors might only waste 5%.
Enter your project dimensions, select your sheet size and application type, and get an accurate count including waste factor, staggered layout pattern recommendations, and 2026 material costs. We'll show you the optimal way to arrange sheets for structural integrity and minimum waste.
How to Use the Plywood Calculator
- 1Select your application type (subfloor, wall sheathing, roof sheathing, or general coverage).
- 2Enter the length and width of the area to cover in feet and inches.
- 3Choose your sheet size: 4×8 (standard), 4×10, or 4×12 feet.
- 4Select the panel type and thickness appropriate for your application.
- 5Set the waste factor based on project complexity (5-20%).
- 6Review total sheets needed, layout diagram, and material cost estimate.
- 7Print your materials list with cutting diagram for the lumber yard.
- 8Order panels allowing for the recommended waste factor.
Formula
Sheets = (Area ÷ Sheet Coverage) × (1 + Waste Factor), rounded upCalculate total area to cover, divide by the coverage of one sheet (32 sq ft for 4×8), multiply by waste factor, and always round up to whole sheets. Example: 384 sq ft floor ÷ 32 sq ft/sheet = 12 sheets × 1.10 waste = 13.2, rounded to 14 sheets.
Plywood vs OSB: Choosing the Right Panel
Both are structural panels, but they have different characteristics:
OSB (Oriented Strand Board):
| Pros | Cons |
|---|---|
| 20-30% less expensive | Swells more when wet |
| Available in larger sizes (4×10, 4×12) | Edges more vulnerable to moisture |
| Consistent density throughout | Heavier than plywood |
| No core voids | Slower to dry if wet |
| Excellent for subfloors, walls, roofs | Not recommended for exposed applications |
Plywood:
| Pros | Cons |
|---|---|
| Better moisture resistance | More expensive |
| Holds fasteners better at edges | May have core voids |
| Lighter weight | Limited to 4×8 standard |
| Faster drying if wetted | Varying layer quality |
| Required by some flooring manufacturers | Surface quality varies by grade |
Application Recommendations:
| Application | Best Choice | Why |
|---|---|---|
| Subfloor | OSB T&G 3/4" | Cost, performance, no blocking needed |
| Wall sheathing | OSB 7/16" | Cost-effective, structural |
| Roof sheathing | OSB 1/2" or 7/16" | Cost, span ratings |
| Underlayment | Plywood 1/4" | Smoother surface, better adhesion |
| Exterior exposure | Plywood | Better moisture handling |
| Tile substrate | Plywood | Required by most tile warranties |
Sheet Sizes and Coverage
Standard panel sizes and their coverage:
Common Sheet Sizes:
| Size | Coverage | Weight (OSB) | Weight (Plywood) |
|---|---|---|---|
| 4×8 | 32 sq ft | 47-77 lbs | 40-70 lbs |
| 4×10 | 40 sq ft | 59-96 lbs | 50-88 lbs |
| 4×12 | 48 sq ft | 71-115 lbs | 60-105 lbs |
Weight varies by thickness and product type
Thickness Options:
| Thickness | Common Applications | Weight/4×8 (OSB) |
|---|---|---|
| 1/4" | Underlayment, paneling | 24 lbs |
| 3/8" | Sheathing (non-structural) | 31 lbs |
| 7/16" | Wall sheathing, roof | 37 lbs |
| 15/32" (1/2") | Roof sheathing | 42 lbs |
| 19/32" (5/8") | Heavy-duty roof | 52 lbs |
| 23/32" (3/4") | Subfloor | 60 lbs |
| 1-1/8" | Heavy-duty subfloor | 85 lbs |
Span Ratings Explained: Panel stamps show ratings like "32/16" or "24/16":
- First number: Maximum roof rafter spacing
- Second number: Maximum floor joist spacing
- Example: "24/16" = 24" rafters, 16" joists
Waste Factors by Application
Different projects have different waste characteristics:
Waste Factor Guidelines:
| Application | Waste Factor | Reasoning |
|---|---|---|
| Rectangular subfloor | 5% | Minimal cuts, simple layout |
| L-shaped floor | 8-10% | More cuts at angles |
| Wall sheathing | 8-10% | Windows and doors create waste |
| Gable roof | 10% | Triangle cuts at gable ends |
| Hip roof | 15-20% | Angled cuts on all edges |
| Complex roof | 20% | Multiple valleys, hips, dormers |
| Siding/panels | 10-15% | Cutouts, corners, matching |
Strategies to Reduce Waste:
- Plan your layout - Draw it before cutting
- Use cutoffs - Save large pieces for small areas
- Consider 4×10 or 4×12 - Fewer end joints, less waste on long spans
- Cut accurately - Measure twice, cut once
- Buy a few extra - Cheaper than a second trip
Waste Calculation Example:
- Roof area: 1,500 sq ft
- Hip roof waste factor: 15%
- Required coverage: 1,500 × 1.15 = 1,725 sq ft
- Sheets needed: 1,725 ÷ 32 = 53.9 → 54 sheets
Installation Best Practices
Proper installation ensures structural performance:
Panel Orientation:
- Run panels perpendicular to framing (strength axis across supports)
- Mark panel stamp should be visible after installation
- "This side down" markings indicate textured side for slip resistance
Staggering Joints:
- Offset end joints minimum 4 feet between rows
- Creates stronger, stiffer assembly
- Required by building code for structural sheathing
- Helps prevent telegraph lines in finished floors
Expansion Gaps:
- Leave 1/8" gap at all panel edges
- T&G subfloor: Gap only at butt ends, not tongue/groove
- Gap allows for expansion without buckling
- Use 10d nail as spacer gauge
Fastening Schedule:
| Application | Fastener | Edge Spacing | Field Spacing |
|---|---|---|---|
| Subfloor | 8d ring-shank | 6" | 12" |
| Wall sheathing | 8d common | 6" | 12" |
| Roof sheathing | 8d common | 6" | 12" |
| Underlayment | 3d ring-shank | 3" | 6" |
H-Clips and Blocking:
- H-clips provide edge support between rafters
- Required for roof sheathing without blocking
- Alternative: 2×4 blocking between rafters
- Not needed for T&G panels
Acclimation:
- Store panels flat on stringers at job site
- Cover loosely (allow air circulation)
- Acclimate 24-48 hours before installation
- Don't install wet or frozen panels
2026 Plywood and OSB Pricing
Current material costs for structural panels:
OSB Pricing (per sheet):
| Thickness | 4×8 | 4×10 | 4×12 |
|---|---|---|---|
| 7/16" | $12-18 | $16-22 | $20-28 |
| 15/32" (1/2") | $15-22 | $20-28 | $25-35 |
| 19/32" (5/8") | $22-30 | $28-38 | $35-48 |
| 23/32" (3/4") | $28-40 | $36-50 | $45-65 |
| 23/32" T&G | $32-45 | $42-58 | $52-72 |
| 1-1/8" T&G | $48-65 | - | - |
Plywood Pricing (per sheet, CDX):
| Thickness | 4×8 | Notes |
|---|---|---|
| 1/4" | $15-22 | Underlayment, BC grade for tile |
| 3/8" | $22-30 | Utility sheathing |
| 1/2" | $28-38 | Roof, walls |
| 5/8" | $35-48 | Heavy-duty applications |
| 3/4" | $45-60 | Subfloor, shelving |
Cost Comparison per 100 SF:
| Application | OSB Cost | Plywood Cost |
|---|---|---|
| 7/16" wall sheathing | $38-56 | $55-75 |
| 1/2" roof sheathing | $47-69 | $88-119 |
| 3/4" subfloor | $88-125 | $141-188 |
| 3/4" T&G subfloor | $100-141 | $156-219 |
Price Factors:
- Prices vary by region and season
- Lumber prices fluctuate significantly
- Bulk orders may qualify for contractor pricing
- Delivery adds $50-150 per order
Subfloor Installation Guide
Proper subfloor installation prevents squeaks and problems:
Subfloor Specifications:
| Joist Spacing | Minimum Panel | Recommended |
|---|---|---|
| 16" OC | 19/32" (5/8") | 23/32" (3/4") T&G |
| 19.2" OC | 23/32" (3/4") | 23/32" T&G |
| 24" OC | 7/8" or 1" | 1-1/8" T&G |
T&G (Tongue and Groove) Benefits:
- No blocking needed between joists
- Prevents differential deflection
- Reduces/eliminates floor squeaks
- Provides edge support
- Faster installation
Subfloor Installation Steps:
-
Preparation:
- Ensure joists are level and crowned up
- Apply glue to joist tops
- Snap chalk lines marking joist centers
-
First Row:
- Start at corner, groove edge toward wall
- Leave 1/8" gap at walls
- Nail into joists, 6" on edges, 12" field
-
Subsequent Rows:
- Apply glue to tongues
- Tap tongue into groove with block
- Stagger end joints 4' minimum
- Use scrap at row starts to stagger
-
Fastening:
- Ring-shank or screw-shank nails
- Or construction screws
- 6" on edges, 12" in field
- Keep fasteners 3/8" from edges
Squeak Prevention:
- Use construction adhesive on all joists
- Pull panels tight before nailing
- Don't overdrive fasteners
- Fill any gaps with shims
Roof Sheathing Guide
Roof sheathing requires specific considerations:
Roof Sheathing Requirements:
| Rafter Spacing | Minimum Thickness | With H-Clips |
|---|---|---|
| 16" OC | 7/16" | 3/8" |
| 24" OC | 1/2" | 7/16" |
| 32" OC | 5/8" | 1/2" |
| 48" OC | 3/4" | 5/8" |
H-Clip Installation:
- Place at mid-span between rafters
- One clip per panel edge
- Provides edge support without blocking
- Required unless edges are blocked
Pitch Factor for Coverage:
| Pitch | Factor | 1000 SF Footprint = |
|---|---|---|
| Flat | 1.00 | 1,000 SF panels |
| 2/12 | 1.01 | 1,010 SF |
| 4/12 | 1.05 | 1,050 SF |
| 6/12 | 1.12 | 1,120 SF |
| 8/12 | 1.20 | 1,200 SF |
| 10/12 | 1.30 | 1,300 SF |
| 12/12 | 1.41 | 1,410 SF |
Roof Sheathing Installation:
- Start at lower corner, panels perpendicular to rafters
- Stagger joints 4' minimum between rows
- Install H-clips at unsupported edges
- Leave 1/8" gap at all edges
- Nail 6" on edges, 12" in field
- Mark rafter locations before roofing
Hip and Valley Cutting:
- Pre-cut angles on ground when possible
- Use circular saw with carbide blade
- Save large cutoffs for opposite side
- Expect 15-20% waste on complex roofs
Wall Sheathing Guide
Wall sheathing provides structural bracing and underlayment:
Wall Sheathing Options:
| Panel Type | Thickness | R-Value | Use Case |
|---|---|---|---|
| OSB | 7/16" | ~0.5 | Standard structural |
| Plywood | 1/2" | ~0.6 | Heavy-duty structural |
| Foam board | 1/2"-2" | 2-10 | Insulation, requires other bracing |
| ZIP System | 7/16"-1/2" | Varies | Sheathing + WRB combined |
Structural vs. Non-Structural:
Structural sheathing (OSB/plywood) provides:
- Racking resistance (holds walls square)
- Shear strength (resists wind/seismic)
- Nail base for siding
- Required at corners minimum
Non-structural (foam) provides:
- Insulation only
- Requires separate bracing (let-in bracing, metal straps)
- Common in some retrofit situations
Installation Around Openings:
- Full sheets first - Install full sheets, then cut openings
- Mark from inside - Drill corners, cut from exterior
- Minimize joints at corners - Don't have seams at window corners
- Flash properly - Install window flashing before window
Fastening Pattern:
| Location | Spacing |
|---|---|
| Panel edges | 6" OC |
| Intermediate studs | 12" OC |
| Around openings | 4" OC |
| Bottom plate | 6" OC |
Weather-Resistant Barrier:
- Install house wrap over sheathing
- Or use ZIP System (integrated WRB)
- Tape all seams
- Install before windows/doors
Pro Tips
- 💡Buy 10% extra sheets for roof sheathing projects—angled cuts on hip roofs create significant waste that simple calculations don't account for.
- 💡Use 4×10 or 4×12 sheets when available for long spans—fewer joints means faster installation and a stiffer assembly.
- 💡Mark joist, rafter, or stud locations on panel edges with chalk before installing the next row for faster nailing.
- 💡Store panels flat on stringers with airflow, covered loosely—never stand on edge or leave exposed to rain.
- 💡Use construction adhesive on all subfloor applications—it dramatically reduces squeaks and increases floor stiffness.
- 💡Snap chalk lines across multiple panels to mark framing locations before nailing in the field.
- 💡Check the span rating stamp on panels—don't assume thickness equals span capability.
- 💡Keep a few cutoff pieces for small areas and patching—matching panels later can be difficult.
- 💡Pre-cut roof angles on the ground when possible—safer and faster than cutting on the roof.
- 💡Use ring-shank or screw-shank nails for subfloors—smooth nails can work loose and cause squeaks.
- 💡Stagger end joints at least 4 feet between rows—required by code and creates a much stronger assembly.
- 💡Leave 1/8" expansion gaps at all panel edges—use a 10d nail as a spacer gauge for consistent gaps.
Frequently Asked Questions
A 12×12 room is 144 square feet. Each 4×8 sheet covers 32 square feet. 144 ÷ 32 = 4.5 sheets. Adding 5% waste: 4.5 × 1.05 = 4.73, so you need 5 sheets. In practice, you'll use 4 full sheets and cut pieces from the 5th sheet for the remaining coverage. The layout would be 3 sheets across (8'+4'), 2 rows (6'+6').
