Plywood Calculator
Count 4×8 plywood sheets for a surface area.
Enter the dimensions of the surface you're covering — a floor, wall, or roof — to get the number of 4×8 plywood or OSB sheets needed, including a waste allowance for cuts.
How it works
A 4×8 sheet covers 32 square feet. Divide the surface area by 32, add a waste allowance for cuts and offcuts, and round up. Stagger the seams when sheathing for strength.
Worked example
Say you're sheathing a 16 ft × 9 ft wall. The area is 16 × 9 = 144 sq ft. One 4×8 sheet covers 32 sq ft, so 144 ÷ 32 = 4.5 sheets. Add 10% for cuts and offcuts (4.5 × 1.10 ≈ 4.95) and round up to 5 sheets. If your wall has a door or large window, you can subtract those openings from the area first — but only deduct full sheets' worth; small openings rarely save a whole sheet because of how the cuts fall.
What changes your estimate
- Sheet orientation. Running sheets horizontally vs. vertically changes how many cuts you make and how much you waste, especially on walls that aren't a clean multiple of 4 feet.
- Thickness isn't in the count. This estimates the number of sheets by area. Thickness (7/16", 1/2", 3/4") affects cost and which job it's rated for, not the sheet count.
- Seam staggering. Sheathing for strength means offsetting seams between rows, which can bump waste slightly on the starter course.
- OSB vs. plywood. Both come in the same 4×8 footprint, so the count is identical — the choice is about cost, moisture exposure, and span rating.