How the plywood calculator works
The 32-square unit
Every 4×8 sheet covers 32 sq ft; area ÷ 32 + waste = the order. The orientation check changes the waste: sheets laid perpendicular to joists (required for strength) fit some rooms cleanly and shred others around closets and jogs. The row-and-course math shows which room you have.
Thickness by application
Subfloors: 3/4" tongue-and-groove (glue + screw, squeak-free). Wall sheathing: 7/16" OSB is the code-standard economy pick. Roof decking: 5/8" minimum at 24" rafter spacing. General shop use: 1/2" birch or sandeply. The thickness ladder prices honestly — subfloor is not the place to save the grade.
Grades and the veneer cheat sheet
Construction ply grades: A-C (one good face), CDX (construction, exterior glue), T&G (flooring). Hardwood ply: baltic birch and maple ply for visible work. The price curve is steep between grades; matching grade to visibility (good faces where eyes land, CDX where they do not) is where sheet-goods budgets are won.