All Calculators/Roof Calculator

Roof Calculator

Calculate roof area, squares, and ridge length from building footprint and pitch.

The roof area calculator applies the slope factor to your building footprint to calculate actual roof surface area, squares, and ridge length for a simple gable roof. Accurate square counts drive shingle, underlayment, and labor estimates. Use it as a starting point before detailed takeoffs.
  • Always add one square (100 sq ft) per valley — the extra material disappears fast in cuts.
  • Measure the building footprint from the ground; climbing the roof to measure adds risk without improving accuracy for initial estimates.
  • Ridge cap shingles are sold separately — calculate ridge length and order 10% over.
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