Enter your Roof Length, Roof Width, Roof Pitch, and Eaves Overhang, then adjust the Waste Factor to find exactly how many Sheets Required to cover your roof — along with your Total Roof Area, Area with Waste, and Exact Sheets count so you never under-order materials.
Sheets Required
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Total Roof Area
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Area with Waste
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Exact Sheets
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Calculate the roof area by multiplying length × width, then adjust for roof pitch using the pitch multiplier. Add overhang and waste factor, then divide by 32 sq ft (one 4×8 sheet) to get the number of sheets needed.
Standard roof sheathing uses 4×8 foot plywood or OSB sheets, which cover 32 square feet each. Common thicknesses are 1/2 inch, 5/8 inch, and 3/4 inch depending on rafter spacing and local codes.
Steeper roof pitches require more material because the actual surface area is larger than the horizontal footprint. The pitch multiplier increases the base area calculation to account for the slope.
A 10% waste factor is typical for roof sheathing to account for cuts, damaged pieces, and odd angles. For complex roofs with many hips, valleys, or dormers, consider 15-20% waste factor.
Yes, always include eaves overhang in your sheathing calculations. Overhangs typically extend 12-24 inches beyond the wall and require additional sheathing material to properly cover.
Both plywood and OSB work for roof sheathing. Plywood is more moisture-resistant and stronger, while OSB is typically less expensive. Both come in 4×8 sheets and provide adequate structural support when properly installed.
Measure the length and width of each roof section at the building footprint level. Don't try to measure the actual sloped surface - the calculator will adjust for pitch automatically. Include any dormers or additions as separate calculations.