Roofing Calculator
Roof area, squares and shingle bundles from your house size and roof pitch, plus underlayment, ridge cap and drip edge for gable or hip roofs.
Result
Roofing squares (with waste)
16.5
- Shingle bundles
- 50
- Roof area
- 1,503sq ft
- Pitch
- 6/12
- Roof angle
- 26.6°
- Underlayment rolls (4 squares each)
- 5
- Ridge and hip length
- 42ft
- Drip edge (10 ft pieces)
- 16
How it’s worked out
- Slope factor for a 6/12 pitch = √(1 + (6 ÷ 12)²) = 1.118
- Footprint with 12 in overhang = 42 × 32 ft
- Roof area = footprint × slope factor = 1,503 sq ft
- Squares = area × (1 + 10% waste) ÷ 100 = 16.53 → 50 bundles at 3 per square
Common questions
What is a roofing square?
A square is 100 square feet of roof. Shingles are priced and sold by the square, usually as 3 bundles per square.
How much waste should I add?
About 10% for a simple gable roof and 15% for hip roofs or roofs with valleys and dormers, to cover cuts and starter courses.
How does pitch change the roof area?
A steeper roof has more surface than its footprint. A 6/12 roof is about 12% larger than the flat area underneath; a 12/12 roof is about 41% larger.