Plywood Sheet Calculator

It multiplies your surface length by width to get the area in square feet, adds your waste percentage, then divides by the area of one panel and rounds up to a whole sheet. So sheets needed equals the ceiling of (length times width times (1 plus waste/100)) divided by (panel length times panel width). A standard 4 by 8 ft panel covers 32 square feet.

A common starting point is 10% for floors and walls and 15% for roofs, since roofs have more cuts around hips, valleys, and the ridge. Selecting a surface in the calculator preloads that suggested waste, but you can type any value from 0 to 90. Add more waste for complex layouts, diagonal runs, or many openings, and less for a simple rectangle.

Yes. Pick a preset like 4 by 9 or 4 by 10, or choose Custom size and enter the panel length and width in feet. The math uses whatever panel area you set, so it works for half sheets, metric-cut panels resized to feet, or any non-standard stock your supplier carries.

The area math is identical: length times width of the surface. The surface choice only changes the default waste suggestion and the labels, such as showing wall height instead of width. For a sloped roof, measure along the actual roof plane (rafter length), not the flat building footprint, so the area reflects the real surface you are sheathing.

You can only buy whole panels, so the calculator always rounds up to the next full sheet after applying waste. That is why the result shows total coverage and leftover coverage: the extra square footage you get from rounding up. That leftover is normal and gives you scrap for small cuts and patches.

Treat it as a planning estimate, not a cut list. It assumes full-panel coverage and a flat waste factor, but real counts depend on panel orientation, staggered seams, and how much scrap you reuse. Confirm against your actual layout and round up before buying, especially for structural sheathing.