Roof Area Calculator
True roof surface area from the footprint and pitch — in squares for ordering.
What is Roof Area?
A roof is longer than the floor it covers, by exactly the slope factor: area ÷ cos of the pitch angle. A 1,400 ft² footprint at 6:12 is about 1,571 ft² of roof — 15% more, which is the difference between the right order and a second delivery. Roofers quote in squares (100 ft² each), and orders include 10–15% waste for starter courses, ridge caps and valley cuts.
How it works
The pitch converts to an angle, whose cosine divides the footprint; the result is shown in square feet and squares. A gable roof is two slopes of this area; a hip roof adds the two ends at the same pitch. Dormers, chimneys and valleys add real surface — the page says where measuring beats assuming.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Type or paste any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.