Roof-squares calculator

A roofing square is the trade's unit for roof surface: one square equals 100 square feet of finished roof. Shingles, underlayment, and labor are all priced by the square, so before line items go into Quick Entry you convert your sloped area to squares by dividing by 100. A 2,400 SF sloped roof is 24 squares. Always work from sloped area, not the flat footprint, or the quantity comes in short.

Enter the footprint — the plan (bird's-eye) area of the roof. Aerial reports and sketch tools typically give footprint. This tool applies the pitch multiplier to convert footprint to sloped area, then to squares, so you don't double-count the slope. If you already have true sloped SF measured on the roof, divide it by 100 directly and skip the pitch step, since the multiplier would inflate an already-sloped number.

Ten percent is the common allowance for a straightforward gable roof; complex roofs with multiple hips, valleys, and dormers often run 12–15% because more shingles are cut and discarded at the diagonals. Starter course and ridge cap add to it as well. The default here is 10% — bump it for cut-up roofs. Waste belongs in the estimate because the material is genuinely consumed; document the roof complexity so the allowance holds up on review.

Three bundles per square is typical for architectural (laminate) shingles, which is the coverage most estimates assume. Three-tab shingles usually run three bundles per square as well, while some heavier designer shingles need four or five. Confirm coverage against the manufacturer's spec for the exact product. To turn squares into a bundle count with waste built in, use the shingle waste and bundles calculator.