Roofing Calculator

A sloped roof has more actual surface area than its flat footprint (the ground area it covers) — the steeper the pitch, the greater the difference. The calculator applies a pitch multiplier (based on the rise-over-12 ratio) to convert your footprint area into the true sloped surface area that actually needs covering.

A roofing square is the standard unit roofers use for estimating and pricing: exactly 100 square feet of roof surface. Materials, labor estimates, and shingle packaging are all typically quoted per square, which is why the calculator converts your total area into squares.

Standard three-tab and architectural asphalt shingles are packaged so that 3 bundles cover 1 roofing square (100 sq ft) — this is an industry-standard convention, though some premium or specialty shingle products may use different bundle coverage, so always check your specific product's packaging.

Real roof installations lose material to cuts around edges, valleys, hips, ridges, and vents, plus occasional damaged pieces — a 10-15% waste factor is a common industry default for simple gable roofs, while more complex roof shapes with many angles may need a higher factor (15-20%).