Sheets Are the Unit That Matters

Projects are measured in square feet, but lumberyards sell plywood in whole sheets. The math is: (project area + waste) ÷ sheet area, rounded up. A 300 sq ft project with 10% waste and 32 sq ft sheets needs 11 sheets — even though 330 ÷ 32 is 10.3, the 11th sheet is unavoidable because sheets don't come in fractions.

Waste Is Layout Reality

Rectangles don't tile perfectly: a 20×15 ft wall sheathed with 4×8 sheets leaves partial bays at the edges, and every door or window opening creates cutouts that rarely yield usable offcuts. The 10% default covers standard layouts; complex framing, sloped walls, or grain-matched panels push waste toward 20%.

Buy the Right Grade, Not Just the Count

Count is only half the order. Subfloor and wall sheathing use CDX (construction grade with exterior glue); cabinet and furniture work needs sanded, void-free panels that cost 50% more per sheet. The price field in Advanced Options lets you model either — CDX near $45, cabinet-grade near $70.