Roofing Calculator

Calculate roofing materials needed for your roof. Estimate shingles, squares, and costs based on roof dimensions and pitch.

This calculator turns roof footprint dimensions and pitch into a material and cost estimate: it multiplies Roof Length by Roof Width to get the flat footprint area, then scales that up by a pitch multiplier -- the geometric factor for a sloped surface versus a flat one -- to get actual Roof Area. Roof Length, Roof Width, and Cost Per Square all move the final numbers by roughly the same proportion for the same percentage change, since each enters the formula as a simple multiplier; there's no single input among those three that dominates the others. Roof Pitch has a real but comparatively small effect on Roof Area, because the pitch multiplier is a square root of (1 + (pitch/12)squared) -- even a steep 8/12 roof only adds about 20% more area than a flat plan, far less than the effect of the same percentage change in Length or Width. Squares Needed simply divides Roof Area by 100 (the roofing industry's standard bundle unit), and Bundles Needed assumes 3 bundles per square, a typical asphalt shingle packaging convention. Cost Per Square is an optional advanced input; leave it at the default or override it with your contractor's actual quote.