Enter your project area, sheet size, and waste factor to get the exact number of plywood or OSB sheets you need. Works for subfloors, walls, roof sheathing, and sheds. Free — no signup required.
Thickness affects cost — select for reference only, it doesn't change sheet count.
| Project | Area | Sheets (4×8) |
|---|---|---|
| 10×12 room floor | 120 sq ft | 5 |
| 12×20 room floor | 240 sq ft | 9 |
| 24×24 garage | 576 sq ft | 20 |
| 10×10 shed walls | 320 sq ft | 12 |
| 1,500 sf roof | 1,500 sq ft | 53 |
A 24×24 ft garage floor (576 sq ft) needs ¾-inch subfloor plywood. Using 4×8 sheets (32 sq ft each) with 10% waste: 576 × 1.10 / 32 = 633.6 / 32 = 19.8 sheets — buy 20 sheets. At $55 per sheet, that's $1,100 in materials. Use tongue-and-groove (T&G) plywood for subfloors to prevent edge movement.
120 sq ft ÷ 32 sq ft per sheet = 3.75 sheets. With 10% waste, buy 5 sheets.
Both work. Plywood handles moisture better and holds fasteners more reliably at edges. OSB is cheaper. For wet areas or where moisture is a concern, plywood is preferred.
Use 10–15% for hip and gable roofs with straightforward geometry. Complex roofs with multiple valleys and dormers: 15–20%.
7/16-inch or 1/2-inch OSB or plywood is standard for wall sheathing. Check your local code — high-wind zones may require 5/8-inch.
Yes. OSB and plywood come in the same standard sheet sizes. The calculation is identical — only thickness options differ from a cost perspective.
Typical Results
💡 For subfloors, buy tongue-and-groove (T&G) plywood — the interlocking edges prevent squeaks and movement under flooring.
Common Mistakes