Roofing Calculator
Roof squares and shingle bundles from pitchRuns in your browser
Pitch factor 1.118: the sloped roof is 11.8% bigger than its footprint. One square = 100 sq ft, about 3 bundles of architectural shingles.
Rough material cost
$2,676Materials only: no tear-off, drip edge, ridge cap, flashing or labor. Rough 2026 US prices for architectural asphalt shingles.
Material estimates only. Round up, buy a little extra, and check with your supplier. Structural work (footings, framing, roofs) must follow local building codes; consult a licensed contractor where required.
How it works
Formulas
Roof area = (length + 2 × overhang) × (width + 2 × overhang) × √(1 + (pitch ÷ 12)²)Squares = roof area × (1 + waste %) ÷ 100; bundles = squares × 3Worked example
Input: 50 × 30 ft house, 1 ft overhang, 6/12 pitch, 10% waste.
- Footprint 52 × 32 = 1,664 sq ft.
- × 1.118 = 1,860 sq ft of roof.
- × 1.10 ÷ 100 = 20.5 squares → 62 bundles.
Result: About 20.5 squares, 62 bundles.
Limits
- Assumes a simple roof where every plane has the same pitch. Measure complex roofs plane by plane.
How to use
- 1Enter the house length and width (outside walls).
- 2Add the eave overhang.
- 3Choose the roof pitch (rise per 12 in of run).
- 4Read squares, bundles and underlayment rolls.
FAQ
What is a roofing square?
100 square feet of roof. Architectural asphalt shingles usually come 3 bundles to a square.
How does pitch change the roof area?
A sloped roof is bigger than the footprint it covers. Multiply the footprint by √(1 + (rise/12)²): 1.054 for 4/12, 1.118 for 6/12, 1.202 for 8/12, 1.414 for 12/12.
How much waste should I allow?
About 10% for a simple gable roof and 15% for hip roofs, valleys and dormers.
Can I use metric units?
Yes. Switch to Metric and enter meters and centimeters; results show cubic meters, square meters or tonnes alongside US units.