Roof area, squares and shingle bundles, from your footprint and pitch.
Roofing squares needed
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Actual roof area
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Shingle bundles
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Estimated cost
A geometric estimate for a simple roof shape. Hips, valleys, dormers and complex rooflines need more material and waste than a simple rectangular estimate allows for — a roofer's measurement is more reliable for ordering.
How this works
Pitch multiplier = √(1 + (rise ÷ 12)²)
Roof area = footprint × pitch multiplier
Squares = (roof area ÷ 100) × (1 + waste %) — one "square" is 100 sq ft of roofing
A steeper roof has more actual surface area than its footprint suggests — a 6/12 pitch adds about 12%, a 12/12 (45°) pitch adds about 41%.
A "square" in roofing is exactly 100 square feet, regardless of shingle size — it is the standard unit roofers and suppliers order by.
3 bundles per square is standard for typical three-tab or architectural shingles; check your specific product, since some premium shingles use different bundle counts.
Currency
Amounts follow the currency selected above.
What is a roofing "square"?
A unit equal to 100 square feet of roof surface — it is how roofing material is priced and ordered, independent of individual shingle size.
How do I find my roof pitch?
It is usually given as "X in 12" — for every 12 inches of horizontal run, the roof rises X inches. 4/12 is a gentle slope, 6/12 is moderate, and 9/12 or steeper is a steep roof. Check building plans or measure with a level and tape.
Why is the roof area bigger than the building footprint?
The footprint is the flat horizontal area the building covers, but the roof surface is tilted at the pitch angle, which stretches its actual area — the steeper the pitch, the bigger the difference.
How many bundles of shingles do I need for a 1,500 sq ft house?
It depends on the pitch — at a typical 6/12 pitch, a 1,500 sq ft footprint gives about 1,680 sq ft of actual roof, or roughly 18.5 squares with 10% waste, needing about 56 bundles at 3 per square. Enter your own footprint and pitch above for an exact figure.