Interactive Roof Measurement Calculator
Upload an aerial roof image, calibrate one known horizontal measurement, then classify each exterior roof edge as an eave or rake and add ridges, hips, and valleys to estimate projected and sloped roof area, total perimeter, and roofing squares.
Your image is processed entirely in your browser. It is never uploaded to our servers.
Frequently asked questions
How does image calibration work?
Draw a line over a known horizontal distance on the aerial image (for example, a wall length), enter the real-world length, and the calculator computes a units-per-pixel scale that is applied to every other line you trace.
Can one calibration measurement scale the entire image?
Yes, as long as the image is a true top-down view with consistent scale. Oblique or perspective imagery will produce errors because the pixel-to-distance ratio changes across the frame.
Is the image uploaded to your servers?
No. Your image stays in your browser. The calculator never uploads it. If you choose to email yourself the PDF and CSV exports, only the measurements are sent.
What does a sloped roof area mean versus a projected area?
Projected area is the footprint of the roof as seen from above. Sloped area multiplies that footprint by the pitch factor to estimate the actual roof surface area.