Enter a wall or roof's total area and any window or door openings to find how many plywood sheathing sheets to order.
How to Use the Plywood Sheathing Calculator
Enter the total wall or roof area, then subtract the combined area of any windows and doors it contains — sheathing goes up as full sheets first and gets cut out around openings afterward, but you're not buying material for the hole itself.
Net area, not gross area, is what actually needs sheets:
net area = total area − opening area
sheets = ⌈(net area × (1 + waste %)) ÷ (sheet width × sheet length)⌉Small openings are sometimes not worth deducting at all, since the cutout piece can't be reused elsewhere anyway — a lot of estimators only subtract openings above a certain size (a garage door, a large picture window) and let smaller ones fall inside the waste allowance instead. Use your judgment on where that line sits for a given job; the field is there either way.