Footprint to sloped area
Footprint = length × width. For rise/run input, pitch multiplier = √(rise² + run²) ÷ run. Sloped area = footprint × multiplier.
Free roofing tool
Roof Area Calculator
Calculate sloped roof surface area from footprint dimensions and pitch. Results are planning estimates and should be checked against field measurements or an aerial report.
Inputs
Enter footprint and pitch
Choose feet or meters, then use a rise/run ratio or a known slope multiplier.
Methodology and assumptions
Units and waste
Metric footprints use the source factor 10.7639 square feet per square meter. One roofing square is 100 square feet. Waste is applied after sloped area.
This is a planning estimate, not a field measurement, aerial report, supplier takeoff or guarantee. Confirm dimensions, roof planes, penetrations and ordering requirements before purchase.
Worked example
A 50 × 30 ft footprint is 1,500 sq ft. A 6/12 pitch multiplier is approximately 1.118, producing about 1,677.1 sq ft or 16.77 roofing squares before waste. A 10% waste setting produces about 18.45 purchase squares.
Roof area calculator FAQ
How does a roof area calculator work?
It multiplies footprint length by width, then applies the pitch multiplier to estimate sloped roof surface area.
Can I use meters?
Yes. Enter dimensions in feet or meters; the result includes square feet, square meters and roofing squares.
What is a roofing square?
One roofing square equals 100 square feet of roof area.
Should waste be included in roof area?
Measured roof area and purchase quantity are different. This tool shows sloped area first, then applies the optional waste percentage separately.