Calculate roofing squares, bundles, and cost estimates based on your house dimensions and roof pitch.
Enter your house dimensions and roof pitch
Simple gable: 10-12%, Complex with hips/valleys: 15-20%
Enter your house length and width (the flat footprint). Choose your roof pitch — higher pitches mean more surface area. The pitch factor converts the flat footprint to actual roof surface area. Set your waste factor — 10-12% for simple gable roofs, 15-20% for complex hip roofs with valleys and dormers. Results show squares needed (1 square = 100 sq ft of roof area) and bundle count.
Roofing materials are sold by the square — a unit equal to 100 square feet of roof area. Three bundles of standard asphalt shingles cover one square. But before you can count squares, you need to factor in your roof's pitch: the steeper your roof, the larger its actual surface area compared to the house footprint.
| Pitch | Factor | Multiplier |
|---|---|---|
| 3/12 | 1.031 | Roof is 3.1% larger than footprint |
| 4/12 | 1.054 | +5.4% |
| 6/12 | 1.118 | +11.8% |
| 8/12 | 1.202 | +20.2% |
| 12/12 | 1.414 | +41.4% |
For a 40×30 foot ranch (1,200 sq ft footprint) with a 6/12 pitch gable roof: 1,200 × 1.118 = 1,342 sq ft of roof area = 13.4 squares. After 15% waste: roughly 16 squares = 48 bundles. At $35-45 per bundle, materials alone run $1,700-2,200.