Estimate roofing material for your project. Enter the footprint dimensions and pitch, select your material and the calculator converts flat area to sloped roof area, then calculates squares, bundles and an indicative material cost.
Enter dimensions to see estimate.
A roofing square equals 100 square feet of roof surface area. Most asphalt shingles are sold in bundles of approximately 33 sq ft, so 3 bundles = 1 square.
The pitch multiplier converts your flat (plan) area to actual sloped surface area:
Sloped Area = Flat Area × Pitch Multiplier
A 6/12 pitch has a multiplier of 1.118, meaning a 1,000 sq ft footprint produces approximately 1,118 sq ft of actual roof surface — about 11.2 squares.
At 3 bundles per square and a 6/12 pitch (multiplier 1.118): 1,000 × 1.118 = 1,118 sq ft ÷ 100 = 11.18 squares × 3 bundles = 34 bundles. Add 10% waste to order 38 bundles.
Asphalt shingle replacement typically costs $3.50–$6.00 per sq ft installed (materials + labor) in the US, or $8,000–$16,000 for an average 2,000 sq ft home. Metal roofing runs $8–$14 per sq ft installed.
Only if the existing plywood or OSB decking is soft, rotted or delaminated. A reputable contractor will inspect decking after removing the old shingles and replace damaged sections before installing new roofing.