Roofing Material Calculator

A roofing square is 100 square feet of roof area. It is the standard unit for ordering roofing materials. To calculate how many squares a roof has, divide the total square footage by 100. For example, a 2,000 square foot roof = 20 squares.

Three-tab asphalt shingles typically come in 3 bundles per square (33.3 sq ft per bundle). Architectural (dimensional) shingles often require 4 bundles per square due to their thicker, heavier design, though this varies by manufacturer. Always check the bundle's coverage listed on the package.

A 10-15% waste factor is standard for a simple gable roof. Add 15-20% for hip roofs, cut valleys, and complex roof lines. Steep pitches also require more material. Always buy in whole bundles and round up, not down.

Roof pitch is the rise in inches per 12 inches of horizontal run (e.g., 6/12 pitch rises 6 inches per foot). Steeper pitches have more surface area than their footprint suggests. This calculator accounts for pitch by multiplying the footprint area by a pitch factor.

Underlayment (roofing felt or synthetic) is required in most building codes as a secondary moisture barrier beneath shingles. Standard asphalt felt comes in 15-lb (covers ~4 squares per roll) and 30-lb (covers ~2 squares per roll) weights. Synthetic underlayment covers more per roll and is lighter and more tear-resistant.