Roof Area Calculator: Work Out Your Sloped Roof Size from the Ground (UK)
By the Professional Roofers team
Updated 2026 · Independent cost guide
Your roof is bigger than your house footprint, because the slope adds length. This calculator takes your building’s plan dimensions and roof pitch and returns the true sloped roof area, the number that drives every re-roof quote and tile order. Measure the footprint at ground level and you never need to climb up.
Calculate your roof area
Geometry only, for budgeting and ordering. It treats the roof as a clean shape and does not deduct for chimneys or dormers, or add for valleys. For a complex roof, treat the result as a close starting point.
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