Enter your roof footprint and pitch to get the true roof area in squares and the number of shingle bundles. Roofing is measured in squares of 100 ft², and steeper pitches increase area through a slope factor.
You need approximately
12.3 squares
1,230 ft² of roof · 26.57° slope
Shingle bundles
37 bundles
Slope factor
×1.118
Footprint
1,000 ft²
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Field notes
Order by the square but buy in whole bundles — three bundles cover a square of architectural shingles, and you'll want the extra for ridge caps and starter courses the footprint math doesn't include. Steep and cut-up roofs (valleys, hips, dormers) waste closer to 15% than 10%. If you can't safely measure the roof itself, measure the footprint and let the pitch factor do the work, then add a bundle.
How the roofing calculator works
The math behind the tool:
roof area = footprint area × slope factor(pitch)
squares = roof area ÷ 100 × (1 + waste%)
A roofing square is 100 ft² of roof surface. Divide your total sloped roof area by 100 to get squares; a 2,000 ft² roof is 20 squares.
How does roof pitch affect material?
Pitch increases the sloped area above the flat footprint. A 6/12 pitch has a slope factor of about 1.118, so it needs roughly 12% more material than the footprint alone.
How many bundles of shingles are in a square?
Most architectural asphalt shingles come three bundles to the square (100 ft²), so a 20-square roof needs about 60 bundles plus waste.