Roof Area Calculator
Determines total roof surface area from base footprint and pitch for material ordering
Length of the building footprint
Width of the building footprint
Rise in inches for every 12 inches of horizontal run
Enter dimensions and pitch to calculate
Total roof surface area adjusted for pitch
1 square = 100 sq ft of roofing material
Frequently Asked Questions
How do I calculate roof area from the ground?
Measure the building footprint (length x width) and determine the roof pitch. Multiply the footprint area by the pitch multiplier. For a 6:12 pitch, the multiplier is about 1.118. A 2,000 sq ft footprint with a 6:12 pitch has roughly 2,236 sq ft of roof area.
What is a roofing square?
A roofing square is a unit equal to 100 square feet of roof area. Roofing materials like shingles are sold by the square. A roof with 2,500 square feet of area needs 25 squares of shingles, plus extra for waste and starter strips.
How much extra roofing material should I order?
Order 10-15% extra for a standard gable roof. Complex roofs with hips, valleys, dormers, or many penetrations may need 15-20% extra due to increased cutting and waste. It is better to have surplus than to run short mid-project.
Does this calculator work for hip roofs?
This calculator gives a simple gable roof approximation. Hip roofs have a similar total area to gable roofs with the same footprint and pitch, so the estimate is close. For precise hip roof calculations, you would need to account for the hip rafter geometry separately.
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