Roofing Calculator
Enter your values below and click Calculate for instant results.
Roof Footprint (ground-level dimensions)
ft
ft
Calculate roofing squares and shingle bundles from roof dimensions and pitch.
Enter your values below and click Calculate for instant results.
Roofing materials are measured in squares. One square equals 100 square feet of roof surface. A typical 3-tab shingle comes in bundles that cover one-third of a square, so three bundles equal one square. Most roofing estimates and contractor bids are expressed in squares, so understanding this unit is essential for cost comparisons.
The ground-level footprint of a house is not the same as the actual roof area. A pitched roof covers more surface than the flat area below it because it extends at an angle. This calculator applies a pitch multiplier (the slope factor) to convert footprint area to actual roof surface area.
A 6/12 pitch means the roof rises 6 inches for every 12 inches of horizontal run. The slope factor for a 6/12 pitch is approximately 1.118, meaning the actual roof area is about 11.8% larger than the footprint. Steeper pitches have higher multipliers, with a 10/12 pitch requiring about 30% more material than a flat roof of the same footprint.