Plywood / OSB Calculator — ft to sheets, cost
How to use this calculator
Pick a shape — Rectangle, L-Shape, or paste a known square footage. Choose the panel size (4×8 is the US standard; 4×10 and 5×5 for special runs), thickness, and material. The number you order is what drives your delivery — net sheets is theoretical; the headline rounds up after waste because lumberyards only sell whole panels.
Sheathing rule of thumb: 7/16″ OSB for walls, 15/32″–19/32″ for roofs, 23/32″ T&G for subfloors at 16″ o.c. joists. Bump waste to 15–20% for hip roofs, dormers, or rooms with lots of trim cuts.
Saved Calculations
| Time | Shape | Area ft² | Material | Thick | Sheets | Weight | Cost |
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How to Use the Plywood / OSB Sheet Calculator
Pick a shape — rectangle, L-shape (footprint minus a cutout), or enter a known square footage. Choose the sheet size, panel thickness, and material (plywood, OSB, or MDF), then set a waste factor for trim cuts and fitting around obstructions. Net sheets is the bare area divided by sheet coverage; the headline figure rounds up after adding waste, since you buy whole panels.
Formulas
Net sheets = area ÷ (sheet length × sheet width). Purchased sheets = ceil(net × (1 + waste%)). A 4×8 ft panel covers 32 ft²; 4×10 = 40 ft², 4×12 = 48 ft², 5×5 = 25 ft². Panel weight = density × (sheet area × thickness/12), using plywood ≈34, OSB ≈37, MDF ≈48 lb/ft³.
Sheet Sizes, Thickness & Waste
Per IRC and APA / PS 1-19 sheathing practice, common thicknesses are 3/8" (underlayment), 1/2" (wall sheathing), 5/8"–3/4" (roof and subfloor), and 1-1/8" tongue-and-groove for wide-spaced joists. Use 10% waste for plain sheathing or subfloor runs, 5% for simple rectangles, and 15–20% for roofs with hips, valleys, or many openings.
Related Calculators
Working out the framing under these panels? Size the structure with the floor joist span calculator and tally framing lumber with the board feet lumber calculator or the stud wall calculator. For exterior projects, the deck calculator and fence calculator cover decking and fence boards. Need metric panels? Switch to the metric plywood / OSB calculator.
Ordering tips
Three calls that ruin a panel takeoff. Stagger the joints — APA E30 requires ½-sheet offset on roofs and floors, so order 1–2 extra sheets beyond the rounded number for the end pieces. Match grade to job — CDX (≈$45–65 per ¾″ 4×8 in 2025) is fine for sheathing; sanded BC or A/C plywood (≈$70–110) is what you want when the face shows; OSB ($30–45) is wall/roof only, never under tile or in a wet floor. Allow for H-clips or T&G — roof sheathing on rafters >24″ o.c. needs H-clips at panel edges per IRC R803.2.3; subfloors over joists at 24″ o.c. need 23/32″ T&G, not ½″ flat. Buying a whole unit (50 sheets) is usually cheaper than 30 loose sheets — ask the yard.
FAQ
Does the count include waste? Yes — the headline "Sheets Needed" already adds your waste percentage and rounds up to whole panels. "Sheets (net)" is the theoretical minimum with zero offcuts.
Why is OSB heavier than plywood? OSB is denser (≈37 vs ≈34 lb/ft³); MDF is heaviest at ≈48 lb/ft³. A 4×8 × 3/4" sheet runs roughly 60–70 lb plywood, 70–78 lb OSB, 85–97 lb MDF.
How accurate is the cost? It is sheets × your price per sheet. Get a current panel quote and confirm thickness and grade (CDX vs sanded) before ordering.
