Free planning tool
Roof area calculator
Estimate the surface of two equal, uninterrupted roof planes. Include eave overhang as horizontal distance and gable overhang along the ridge. Review the result with your supplier before ordering.
How the result is worked out
Slope factor = √(1 + (rise ÷ half-span)²). Area = 2 × (half-span + horizontal eave overhang) × slope factor × (length + 2 × gable overhang). Order area adds your chosen waste percentage.
What to keep in mind
Excludes dormers, valleys, penetrations and separate roof sections. Does not calculate snow loads, truss sizes, fasteners, flashing or safe roof access. Waste is your assumption, not a supplier specification.
Read the related guide: How to estimate an A-frame roof’s surface area →