Roofing Calculator
Estimate shingle bundles and squares with roof pitch adjustment.
Roofing Materials Calculator
Estimate sloped roof area, roofing squares, and bundles from footprint and pitch.
Roof area estimate
Estimated bundles
37
- Pitch multiplier
- 1.118
- Sloped roof area
- 1118.0 sq ft
- Area with waste
- 1229.8 sq ft
- Roofing squares
- 12.30
Uses a single slope multiplier on the entered horizontal footprint. Complex roofs, hips, valleys, dormers, underlayment, ridge caps, code, and manufacturer bundle coverage require separate takeoff.
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What This Calculator Does
The Roofing Calculator computes total sloped roof surface area, industry roofing squares (100 sq ft units), and standard shingle bundle counts from a ground building footprint, roof pitch slope, and waste allowance.
How It Works
Roof slope pitch (rise in inches per 12 inches of run) calculates a geometric multiplier via the Pythagorean theorem: sqrt(1 + (rise/12)^2). Multiplying ground footprint by this factor yields actual sloped surface area. Factoring in waste (typically 10% to 15%) gives total order area, which is divided by 100 for roofing squares and by bundle coverage (typically 33.3 sq ft, or 3 bundles per square).
Example
A 2,000 sq ft footprint with a 6/12 pitch has a multiplier of 1.118, yielding 2,236 sq ft of roof area. With 10% waste, order coverage is 2,460 sq ft (24.6 squares), which rounds up to 74 shingle bundles.
Formula
Multiplier = Sqrt(1 + (Rise in / 12)²)Roof Area = Footprint sq ft × MultiplierSquares = Order Area / 100; Bundles = Ceil(Order Area / Bundle Coverage)Reading the Results
Roofing squares
One roofing square equals 100 square feet of actual roof surface area.
Bundles to purchase
Total shingle packages required, assuming standard asphalt 3-tab or architectural shingle coverage.
Area with waste
Total ordering square footage including ridge caps, valley cuts, eaves, and starter strips.
Frequently Asked Questions
What is a roofing square?
In the construction and roofing trades, a square is a standardized unit of measure equal to exactly 100 square feet of roof surface.
How many bundles of shingles make a square?
Standard architectural and 3-tab asphalt shingles are packaged with 3 bundles per square (each bundle covering approximately 33.33 sq ft).
Why is roof area larger than ground footprint?
Because roofs are angled, their sloping surface area is always larger than the flat horizontal footprint below. Steeper roof pitches create significantly more surface area.