Roofing Calculator Roofing Calculator Estimate roofing materials (shingles, underlayment) needed. Roof Area Calculation Calculation Method: Use Ground Footprint & Pitch Enter Known Roof Surface Area Measure the length and width of the building at ground level (including overhangs) to get the footprint. Footprint Length (feet): Footprint Width (feet): Roof Pitch (Rise/12" Run): 1/12 2/12 3/12 4/12 5/12 6/12 7/12 8/12 9/12 10/12 11/12 12/12 13/12 14/12 15/12 16/12 17/12 18/12 Custom Multiplier Select the vertical rise for every 12 inches of horizontal run. (?) Total Roof Surface Area (sq ft): Enter the actual measured area of all roof planes combined. Materials & Waste Waste Overage (%): Typically 10-15% for gable roofs, 15-20% for complex hip roofs or valleys. Coverage per Bundle/Roll (sq ft): Shingles (Most Bundles ≈ 33.3 sq ft) Underlayment / Felt (1 Roll ≈ 100 sq ft / 1 Square) Underlayment / Felt (1 Roll ≈ 200 sq ft / 2 Squares) Underlayment / Felt (1 Roll ≈ 400 sq ft / 4 Squares) Synthetic Underlayment (1 Roll ≈ 1000 sq ft / 10 Squares) Custom Coverage (sq ft) Check packaging. Shingles cover ~1/3 square per bundle. Underlayment varies. Calculate Roofing Materials
