Roof Area Calculator
Convert a building footprint into the true sloped roof surface area you actually have to cover.
Roofing calculators
Roof surface area and sheet counts, and the fence calculator that shares the same linear estimating logic. Roof geometry is simplified to a symmetrical gable — check complex roofs with your roofer.
What you can calculate here
- True roof surface area from the footprint, pitch and eaves overhang.
- Slope length for rafter and sheet ordering.
- Sheet counts including side and end laps.
Roofing calculators
Roofing Sheet Calculator
Work out how many profiled sheets, panels or tiles you need to cover a roof, allowing for side and end laps.
Roofing questions
Why is roof area larger than the building footprint?
Because the slope and the eaves overhang add surface. A pitched roof always covers more area than the ground plan underneath it.
How much lap do profiled sheets need?
Typically 10–20 % total lap depending on profile and pitch. Steeper roofs and exposed sites need more.