Construction & Materials
Roofing Calculator
Roofing — roofing Calculator works out roof area from the footprint and pitch, then applies the waste % you enter and expresses it in roofing squares. This page runs that same calculation on your numbers, in your browser: no signup, no uploads, nothing stored.
Use Roofing Calculator to estimate roofing squares: give it your footprint length, footprint width, pitch rise per 12 and waste %, press Calculate, and read off the roof area in squares — all worked out on your device.
Estimate only — not engineering or roofing advice. Roof area depends on the footprint, pitch and waste % you enter; underlayment, overlaps and accessories are not counted, so confirm with your supplier.
About this calculator
Roofing Calculator works out roof area from the footprint and pitch, then applies the waste % you enter and expresses it in roofing squares. It matters before you buy: a clean volume estimate plus a waste allowance beats a guess every time. Here is the calculation on real numbers: A roof plane 10 m × 6 m = 60 m². Adding 10% for overlaps and offcuts means ordering about 66 m² of covering. For your own figures, use the calculator above — same method, your inputs, computed on-device.
How to use
- Enter the footprint length in feet.
- Enter the footprint width in feet.
- Enter the pitch as the rise per 12 and a waste percentage.
- Tap Calculate to see roof area, squares, and the slope factor.
Why use the Roofing Calculator
Instant
Every quantity is worked out on your device the moment you tap Calculate.
Private
The numbers you enter stay in your browser and are never uploaded or saved.
Free
No signup, no paywall, and no ads placed inside your results.
Works offline
Once the page has loaded it keeps working on a weak or dropped connection.
Mobile-first
Laid out for phones and tablets on site just as much as for desktops.
Planning estimates
Results are simplified planning estimates; real material needs vary by product size, waste, layout, local codes, and site conditions, so confirm before you buy or build.
Common uses
Use it when measuring roof area
Use it when planning a re-roof
Use it for contractor and client quotes
Use it when adding a waste margin
Use it for estimating shingles or sheets
Use it for a pitched-roof project
Technical notes
Roofing Calculator works out roof area from the footprint and pitch, then applies the waste % you enter and expresses it in roofing squares.
Includes the waste % you enter; confirm coverage rates and material sizes with your supplier before ordering.
The tool works offline once loaded, since every computation is client-side.
Worked example
A roof plane 10 m × 6 m = 60 m². Adding 10% for overlaps and offcuts means ordering about 66 m² of covering.
FAQ
Does a steeper pitch increase the roof area?
Yes. A steeper pitch raises the slope factor, so the sloped area is larger than the flat footprint.
Does the Roofing Calculator upload my footprint?
No. The Roofing Calculator runs in your browser and your figures are never sent to a server.
What is a roofing square?
A square is 100 square feet of roof area, and the tool rounds the area up to whole squares.
How is the slope factor found?
It is the square root of the rise squared plus 144, divided by 12, where 12 is the run.