Enter roof footprint dimensions, pitch, and waste to calculate roofing squares, shingle bundles, and material cost.
How to Use the Roofing Material Calculator
Enter the building's footprint length and width, not the roof's actual sloped dimensions, along with the pitch, and the calculator derives the true roof area on its own. Add a waste percentage and your supplier's price per square to see bundle counts and total cost.
A roof's footprint and its actual surface area are two different numbers, and the gap between them grows with pitch. A flat roof's footprint and its roof area are identical; a steep one can run 15–40% larger than the building beneath it, because the surface travels up an incline rather than lying flat.
From Footprint to Squares
slope multiplier = √(1 + (pitch ÷ 12)²)
roof area = footprint area × slope multiplier
squares = (roof area × (1 + waste%)) ÷ 100Roofers price and order material in "squares," 100 square feet each, a unit that predates most other construction measurements still in daily use. Shingle manufacturers then package each square across a fixed number of bundles, three being the standard for most three-tab and architectural shingles, though some heavier profiles ship four to a square.
Waste Isn't Optional
Hips, valleys, ridge caps, starter courses, and the occasional cut-and-toss piece all eat into coverage that a pure area calculation doesn't see. Ten percent is reasonable for a simple gable roof; a complex roof with multiple valleys and dormers should run higher, sometimes 15–20%.
Price per square defaults to zero on purpose — shingle, tile, and metal roofing prices vary enormously by material and region, so plug in your own supplier quote rather than trusting a guessed number.