Roofing Calculator
Enter your roof's footprint area and pitch to estimate the actual sloped roof area and how many squares of shingles you'll need.
Last updated: September 5, 2026
Frequently asked questions
How many squares of shingles do I need for a 1500 sq ft roof with a 6/12 pitch?
A 6/12 pitch increases the flat footprint area by about 11.8% - 1500 sq ft becomes roughly 1677 sq ft of actual roof, or about 19 squares including a 10% waste allowance.
What is a roofing square?
A roofing square is a standard unit equal to 100 sq ft of roof area - shingles and other roofing materials are typically priced and sold by the square.
Why does roof pitch matter for material estimates?
A steeper pitch means more actual roof surface area than the same footprint on a flatter roof, since the roof plane is longer at a steeper angle - this calculator's pitch factor accounts for that difference so the material estimate reflects the true surface, not just the building's footprint.
What's included in a typical roofing material estimate beyond shingles?
Beyond the shingles themselves (measured in squares), a full roofing estimate usually accounts for underlayment, starter strips, ridge cap shingles, and flashing - this calculator estimates the shingle quantity specifically, which is the largest cost component, but always add a margin for these additional materials.
How many squares do I need for a 2000 sq ft footprint with a 4/12 pitch?
A 4/12 pitch gives a multiplier of about 1.054, so 2000 sq ft becomes roughly 2108 sq ft of actual roof area. With a 10% waste allowance that's about 2319 sq ft, or 24 squares after rounding up.
Does a steeper roof always need proportionally more waste allowance too?
This calculator applies a flat waste percentage regardless of pitch, but in practice very steep roofs (above roughly 9/12) or roofs with many hips and valleys need a higher waste allowance than a simple roof, since more shingles get cut at odd angles - increase the waste input above 10% for complex, steep rooflines.
What's the difference between 'roofing squares' and plain square footage?
Square footage measures flat area; a roofing square is a sales unit equal to 100 sq ft of the actual sloped roof surface. Because pitch increases the sloped area beyond the footprint, a 1500 sq ft footprint isn't 15 squares of shingles - it's more, which is exactly what the pitch multiplier in this calculator corrects for.