Roof Square Footage Calculator
Calculate roof square footage from house dimensions and pitch. Enter footprint and pitch for actual roof area in sq ft, with waste and squares conversion. Free, no signup.
Roof Area Calculator
Calculate actual roof surface area from plan dimensions and pitch
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Roof sq ft — did you know?
House sq ft vs roof sq ft
House footprint (floor area) is NOT roof area. At 6:12 pitch, roof area is 11.8% more than footprint. 2,000 sq ft house at 6:12 = 2,236 sq ft roof. Always calculate from footprint + pitch.
Sq ft to squares
1 square = 100 sq ft. Divide roof sq ft by 100. 2,236 sq ft = 22.36 → 23 squares. Add 10-15% waste: 23 × 1.12 = 25.76 → 26 squares.
Calculating for multi-slope roofs
Calculate each slope separately: rectangle area × pitch factor. Add all slopes. For hip roofs, add ~4% for hip-end slopes. Subtract chimney/skylight openings (measure their sloped area, not plan area).
Why roofers measure in squares not sq ft
Squares simplify ordering: shingles sold by the square, underlayment by the square, nails by square coverage. "26 squares" is easier to communicate than "2,576 sq ft including waste."
Formulas used
Roof sq ft
sqft = footprint_sqft × (1 ÷ cos(pitch°))
Sq ft to squares
squares = ceil(sqft ÷ 100)
With waste
total = ceil(squares × (1 + waste%))
Hip roof factor
hip_sqft = sqft × 1.04
Frequently asked questions
How do I calculate roof square footage?
footprint_sqft × pitch_factor. 2,000 sq ft at 6:12 (factor 1.118) = 2,236 sq ft. Divide by 100 for squares.
Is house square footage the same as roof?
No. Roof area = footprint × pitch factor. At 6:12, roof is 11.8% larger than footprint. At 12:12, 41.4% larger.
How many squares is 2,000 sq ft roof?
2,000 ÷ 100 = 20 squares. With 12% waste: 20 × 1.12 = 22.4 → 23 squares.
Best free roof sq ft calculator?
One that takes footprint + pitch, calculates sq ft and squares with waste. This tool does all, free.