Roofing Calculator
Calculate roofing squares and shingle bundles for any roof.
Enter dimensions and pitch for material totals including a waste factor and ridge cap estimate.
Roofing material quantity depends on the roof’s actual surface area (not the floor plan area), the pitch factor, and a waste allowance for cuts and overlaps. Roofing is sold in squares (1 square = 100 square feet of coverage), so all calculations convert to squares.
Roof area formula: Roof Area = Floor Plan Area × Pitch Factor
Where:
- Floor Plan Area — the horizontal footprint of the roof in square feet (length × width of the building)
- Pitch Factor — a multiplier that accounts for the slope of the roof (see table below)
Pitch factor table:
- Flat (0/12): 1.00
- 2/12 pitch: 1.02
- 4/12 pitch: 1.05
- 6/12 pitch: 1.12
- 8/12 pitch: 1.20
- 10/12 pitch: 1.30
- 12/12 pitch: 1.41
- 14/12 pitch: 1.54
Squares needed formula: Squares = (Roof Area × Waste Factor) ÷ 100
Waste factor: 1.10 for simple gable roofs; 1.15 for moderate complexity; 1.20 for complex roofs with many hips, valleys, and dormers.
Material cost formula: Total Cost = Squares × Cost per Square + (Ridge Length × Ridge Material Cost) + Labor
Approximate US material costs per square (these vary widely by region and year — get local quotes for budgeting):
- 3-tab asphalt shingles: ~$80 to $120/square
- Architectural (dimensional) shingles: ~$100 to $160/square
- Standing seam metal: ~$350 to $700/square
- Cedar shake: ~$250 to $500/square
- Clay or concrete tile: ~$300 to $600/square
These ranges are reference points only. Material costs change with steel and asphalt prices, and vary heavily by country (clay tile is dramatically cheaper in Spain than in the US, for example).
Worked example: Ranch house with footprint 40 ft × 60 ft = 2,400 sq ft. Roof pitch: 6/12 (factor 1.12). Simple gable (waste 1.10).
- Roof area = 2,400 × 1.12 = 2,688 sq ft
- Squares with waste = (2,688 × 1.10) ÷ 100 = 29.6 → order 30 squares
- If architectural shingles cost $130/square locally: 30 × $130 = $3,900 in materials
- If labor is $200/square locally: 30 × $200 = $6,000
- Total installed: ~$9,900
The calculator uses whatever you enter for material and labor costs — these are just illustrative numbers for the example.