Roofers
Roofing Calculator
Calculate roofing squares and shingle bundles needed for any roof size and pitch.
40′ × 30′ footprint × 1.118 pitch multiplier = 1342 sq ft actual roof area = 13.4 squares. With 15% waste: 15.4 squares × 4 bundles = 62 bundles. Starter strip, ridge cap, and flashing ordered separately.
Common Questions
How do I calculate roofing squares?
Measure the building footprint (length x width). Multiply by the pitch factor for your roof slope. Divide by 100 to get squares. A 40x30 foot building with a 6:12 pitch has about 134 squares of actual roof area.
What is a roofing square?
One roofing square equals 100 square feet of roof surface. This is the standard unit used when ordering shingles and other roofing materials.
How many bundles of shingles per square?
Three-tab shingles need 3 bundles per square. Architectural (dimensional) shingles need 4 bundles per square. Some premium shingles need 5 bundles. Check the manufacturer specs.
How much waste should I add for shingles?
Add 10 percent for a simple gable roof. Add 15 percent for a standard roof with valleys. Add 20 percent or more for a complex hip roof with lots of angles and cuts.
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