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Plywood Calculator

plywood calculator. Sheet count for walls, floors, roofs, and sheathing by area and sheet size.

The Short Answer: A standard 4x8 plywood sheet covers 32 sq ft. A 1,200 sq ft roof deck needs 38 sheets (plus 10% waste = 42 sheets). Common thicknesses: 3/8 inch for wall sheathing, 1/2 inch for roof decking, 3/4 inch for subfloor.

Plywood Calculator

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Plywood Sheet Estimation

Plywood is sold in standard 4x8-foot sheets (32 sq ft each). The main variables are thickness and grade. Thickness determines the application: 3/8" for wall sheathing, 1/2" for roof decking, 3/4" for subfloor and shelving, 1/4" for underlayment and cabinet backs.

Grade matters too: CDX (construction/exterior) is standard for structural sheathing -- hidden behind siding or roofing. Sanded plywood (A-grade face) is for visible applications like cabinets and furniture. Marine-grade plywood is waterproof glue for outdoor or marine use. Cabinet-grade hardwood plywood (birch, oak, maple face) is for fine woodworking.

When estimating, add 10% waste for cuts and fitting. Sheets are heavy (a 3/4" sheet weighs about 70 lb) and awkward to handle alone -- plan for help on delivery and installation.

Frequently Asked Questions

Divide the roof area in square feet by 32 (the coverage per 4x8 sheet) and add 10% for waste and cuts at hips, valleys, and edges. A 1,200 sq ft roof: 1,200 ÷ 32 = 37.5, plus 10% = 42 sheets. Use 1/2" CDX for most residential roofs, 5/8" for 24-inch rafter spacing.

Same calculation: floor area ÷ 32, plus 10%. A 1,000 sq ft floor: 35 sheets of 3/4" tongue-and-groove plywood. T&G plywood is specifically designed for subfloors -- the interlocking edges reduce squeaks and create a stiffer floor. Glue and screw for best results.

The Bottom Line

Free plywood calculator. Sheet count for walls, floors, roofs, and sheathing by area and sheet size. Accurate measurements prevent over-ordering and under-ordering — both cost you money and time. Enter your project dimensions above, add 10% for waste, and order with confidence.

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