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Roofing squares calculator
Converts sloped roof area to squares — the unit the roofing trade bids and orders in.
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How it’s computed
Squares = roof area (sqft) ÷ 100. One square = 100 sqft of roof surface.
Decimal-exact and deterministic: identical inputs always return identical results. This is the same math Ask Donnie’s estimating engine runs — not an approximation, and never a language model doing arithmetic.
Common questions
Plan area or sloped area?
Sloped. If you only have the plan footprint and pitch, run the roof area calculator first — a pitched roof is bigger than its footprint.
Why does roofing use squares?
Convention: materials (shingles, underlayment) and labor are priced per 100 sqft of roof surface, so the whole trade quotes in squares.
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