Roofing
Roofing Shingle Calculator
Estimate roof area, roofing squares, shingle bundles, underlayment, ridge cap, drip edge, waste, and material cost.
Estimated order quantity
0 shingle bundles
Planning estimate only. Verify product specifications, site conditions, and supplier purchase increments before ordering.
How the roofing estimate works
The building footprint is multiplied by a pitch factor calculated from the selected rise over 12 inches of run. Additional roof area is then added. The visible waste allowance covers starter cuts, rakes, hips, valleys, and damaged pieces, but complex roofs should be measured plane by plane.
Roof area: length × width × pitch factor + additional area
Bundles: ceil[roof area × (1 + waste) ÷ bundle coverage]
Roofing squares and bundle coverage
One roofing square equals 100 square feet. Many laminated asphalt shingles use about three bundles per square, but products vary. GAF instructs buyers to use the coverage printed on the bundle; this calculator therefore keeps bundle coverage editable and rounds the purchase quantity up to whole bundles.
Underlayment, ridge cap, and drip edge
Underlayment rolls are based on the roof area with the selected allowance and the net coverage entered. Ridge-cap bundles are calculated only when total ridge and hip length is provided. Drip edge uses the rectangular building perimeter plus 5% and rounds to whole pieces. Confirm overlap, eave/rake details, valleys, starter strips, ventilation, flashing, fasteners, and local code separately.
Worked example
A 40 × 30 ft building with a 4:12 roof has a pitch factor of about 1.054 and a measured roof area of about 1,265 ft². With 10% waste, plan for about 1,391 ft², or 13.91 roofing squares. At 33.3 ft² per bundle, purchase 42 bundles.
Planning notes
- Measure eaves, rakes, hips, valleys, ridges, dormers, and intersecting planes on complex roofs.
- Use the actual net coverage printed on each selected product.
- Do not use footprint-only results for ordering when roof geometry is irregular.
- Roof work is hazardous. Follow manufacturer instructions, fall-protection rules, local code, and qualified professional guidance.
Roofing shingle calculator FAQ
What is a roofing square?
A roofing square is 100 square feet of roof surface. It is an area unit, not a square-shaped package.
How many bundles are in a square?
Many common asphalt shingles use about three bundles per square, but heavier or specialty products may use more. Enter the package coverage printed by the manufacturer.
How much waste should I add?
Ten percent is a common planning starting point for a simple roof. Hips, valleys, dormers, multiple planes, and complex cuts may justify 15% to 20% or a detailed takeoff.
Does this include starter shingles and flashing?
No. Starter strips, valley materials, flashing, ventilation, ice-and-water protection, fasteners, and accessories depend on the roof design and selected system.