Roofing Calculator
A roof is measured on the slope, not the footprint. Enter the building footprint and roof pitch to get the sloped roof area, roofing squares, underlayment rolls and a material estimate for panels or other products sold by the square.
Roofing Calculator
Roofing & Exterior
ft
ft
%
ft²
e.g. metal panel bundle coverage. Leave 0 to skip.
Roof surface area
1,342ft²
124.6 m² · slope factor 1.118×
Material to buy
1.4squares
Underlayment rolls
4rolls (4 squares each)
Ridge + hip cap estimate
4bundles
planning figure ≈ 1 bundle per 4 squares
Calculation breakdown
- 1Footprint:
12.19 × 9.14 = 111.48 m² - 2Pitch factor:
√(1 + (6/12)²) = 1.1180 - 3Sloped area:
111.48 × 1.1180 = 124.64 m² - 4With waste:
× 1.12 = 139.6 m²
Pitch multiplier = √(1 + (pitch/12)²).
Roof area = Footprint area × Pitch multiplier.
Squares = Roof area ÷ 100 ft². Underlayment ≈ 1 roll (4 squares) per 400 ft².