Roof Area Calculator
Estimate your roof area for replacement, repair, or solar panel planning. Enter your building dimensions below.
Steeper roofs have more surface area
This calculator provides estimates based on simplified measurements. Actual roof area may vary due to dormers, valleys, chimneys, and other features. A professional inspection is recommended for accurate quotes.
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call Call 08 7947 8417How the roof area calculator works
We built this on the same method our estimators use on site. You enter the footprint of your building, its length and width, and choose the roof pitch. The tool multiplies that footprint by a pitch factor to account for the slope, because a pitched roof always has more surface than the ground beneath it, then converts the result into square metres and roofing squares.
From experience we allow roughly ten percent on top for cuts, overlaps and waste, so the material figure is realistic rather than a bare minimum. Treat the result as a budgeting estimate: it is accurate enough to plan and compare, but a proper measure-up is what we quote a roof restoration or replacement from.
Roof area calculator FAQs
What is a roofing square?
A roofing square is a trade unit equal to 100 square feet, or about 9.29 square metres. Suppliers and roofers order and price materials in squares, so the calculator converts your area into squares to make quoting and ordering easier.
Why does roof pitch change the area?
A pitched roof always has more surface than the ground it covers. The calculator applies a pitch multiplier to your building footprint, so a steep gable ends up with a larger area than a low-pitch roof on a house of the same size.
How accurate is this estimate?
It is a planning estimate, good enough to budget and compare materials. It cannot see valleys, overhangs, penetrations or access issues, so we always confirm with an on-site measure-up before quoting a repair or replacement.
Should I include the eaves and overhangs?
Measure the footprint of the building including the eaves overhang where you can, since the roof extends past the walls. If you only have wall dimensions, add a little for the overhang, or ask our team to measure it properly.