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Roofing Calculator
Measure the building's footprint at ground level, pick the roof pitch, and this gives you the actual sloped area, how many roofing squares that is, and how many bundles of three-tab or architectural shingles to order.
Your numbers
Result
Roofing squares
16.5
squares
- Shingle bundlesAt 3 bundles per square
- 50bundles
- Actual roof area
- 1,503sq ft
- Order area, incl. waste
- 1,653sq ft
- Footprint incl. overhang
- 1,344sq ft
- Pitch multiplier
- 1.118
How this is calculated
- Footprint = (length + 2 × overhang) × (width + 2 × overhang)
- Pitch multiplier = √(rise² + 12²) ÷ 12 — a 6/12 roof works out to 1.118, so the sloped surface is about 12% larger than the ground it covers.
- Roof area = footprint × pitch multiplier
- Order area = roof area × (1 + waste %)
- Squares = order area ÷ 100. One roofing square is 100 sq ft.
- Bundles = squares × 3, rounded up. Standard three-tab and most architectural shingles run three bundles to the square.
Before you order
- This assumes a simple gable or hip roof. Valleys, dormers and multiple ridges add cut waste — step the waste allowance up to 15%.
- Heavier architectural and designer shingles sometimes run four or five bundles per square. Check the wrapper before you order.
- Ridge cap, starter strip, underlayment and drip edge are separate line items and are not included here.
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