How it works
Roof area = (length + 2 × overhang) × (width + 2 × overhang) × slope factor; squares = area ÷ 100; order = squares × (1 + waste ÷ 100), rounded up; bundles = order × 3.
Free calculator / Roofing
Roofing squares and shingle bundles.
Estimate roof area, squares to order and shingle bundles from the footprint, overhang, pitch and a waste allowance.
Your numbers
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Your answer
A quick example
A 40 × 30 ft footprint with 12-inch overhangs at 6/12 is about 1,503 sq ft, or 15.03 squares. With 10% waste, order 17 squares: 51 bundles.
This is a calculation from numbers you supply, not financial or tax advice. Check assumptions before making a decision.