A house's footprint and its roof's actual surface area are not the same number — a sloped roof covers more material than the flat area underneath it, and the steeper the slope, the bigger that gap gets.
Roof pitch area calculator, not just footprint
Enter your footprint and the roof's pitch (rise per 12 inches of run — a "6:12" roof rises 6 inches for every 12 inches horizontal), and this calculator applies the standard pitch-to-area multiplier so the material estimate reflects the real sloped surface, not the flat footprint.
Roof squares calculator, the unit contractors actually use
Roofing is measured in "squares" — 100 square feet each — not raw square footage. The result converts straight to squares so it lines up with how shingles are quoted and sold.
How many shingles do I need, in actual bundles
At the standard 3 bundles per square for typical 3-tab or architectural shingles, plus your chosen waste factor for cuts, hips, and valleys, you get a bundle count ready to take to the store — not just an area figure you have to convert yourself.
