🏠 Roofing Calculator
Estimate roof surface area, roofing squares, and shingle bundles needed based on your roof's footprint dimensions and pitch.
Roof Details
Your Result
A "roofing square" equals 100 square feet of roof surface. Most standard shingles come 3 bundles per square. Always confirm exact quantities with your roofing supplier.
How the Roofing Calculator Works
Roofers estimate materials in "squares" — each square covers 100 square feet of actual roof surface. Because a pitched roof has more surface area than its flat footprint, the calculator multiplies your footprint area by a pitch multiplier to get the true roof area.
Formula
Actual Roof Area = Footprint Area × Pitch Multiplier
Roofing Squares = Actual Roof Area ÷ 100
Squares (with waste) = Squares × (1 + Waste % ÷ 100)
Shingle Bundles = Squares (with waste) × 3
Understanding Roof Pitch
Roof pitch is expressed as rise over a 12-inch run (e.g., 6/12 means the roof rises 6 inches for every 12 inches of horizontal run). Steeper pitches have more surface area than the building's footprint, which is why the pitch multiplier increases with steepness.
Why Add a Waste Factor?
A waste factor accounts for material lost to cutting, overlaps, hips, valleys, and mistakes. A 10% waste factor is typical for simple gable roofs, while complex roofs with many hips, valleys, or dormers may need 15-20%.
Frequently Asked Questions
What is a roofing square?
A roofing square is a unit of measure equal to 100 square feet of roof surface area. It's the standard unit used by roofers and suppliers to price materials and labor.
How many bundles of shingles are in a square?
Most standard three-tab and architectural shingles come 3 bundles per square, though some heavier or specialty shingles may use 4 or 5 bundles per square. Check your specific product.
Why is my actual roof area larger than the footprint?
A sloped roof surface is longer than the flat building footprint beneath it. The steeper the pitch, the greater the difference, which is captured by the pitch multiplier.