Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Convert a known roof area directly into shingle bundles and ridge cap bundles needed.
If you already know your roof's total surface area -- from a measurement, an appraisal, or the Roofing Calculator or Roof Area Calculator -- this tool skips straight to the materials: shingle bundles and ridge cap bundles, without recalculating the pitch conversion.
Enter your roof's total area and the length of its ridge line (where two roof planes meet at the top).
Squares = (Roof Area × (1 + Waste)) ÷ 100
Shingle Bundles = Squares × 3
Ridge Cap Bundles = Ridge Length ÷ 35 (a common ridge-cap product coverage)
The "3 bundles per square" and "35 linear feet of ridge cap per bundle" ratios are standard for most common asphalt shingle products, but always check your specific manufacturer's coverage rating before finalizing an order.
This tool starts from a finished roof surface area, so the quality of your answer depends on that input. Surface area is larger than the footprint of the house because of the slope. If you only know the footprint, multiply it by the slope factor from the Roof Pitch Calculator first. Do not use the footprint directly, or you will under-order shingles. Also include sections that people forget: attached garages, porch roofs, dormers, and any lower roof levels that are also being replaced.
Suppose a roof measures 2,650 square feet of surface, the ridge line is 48 feet, and you use a 10 percent waste allowance (hypothetical values). Adding waste gives 2,915 square feet, which is 29.15 squares. At 3 bundles per square that is 87.45 bundles, so you would plan for 88. The ridge cap needs 48 divided by 35, or 1.37, which rounds up to 2 bundles. Notice that ridge cap is counted separately from the field shingles. A roof with a complicated shape, with hips and multiple ridges, needs the total length of all ridges and hips added together.
Rather than trusting a rule of thumb blindly, compare the result to your supplier's estimate. If the two differ by more than a bundle or two, ask why. The gap usually comes from different assumptions about waste or about which roof sections are included.
The result covers shingles and ridge cap only. Underlayment, ice and water shield, drip edge, flashing, nails, vents, and roof deck repair are not included. Local codes may also dictate how many layers may exist or which underlayment is required, so check with your local building department. For a complete price, combine the bundle counts with a supplier quote or use the Roofing Cost Calculator.
3 bundles is standard for most asphalt shingles -- always confirm against your specific product's packaging, since coverage can vary slightly by manufacturer.
Round up. Bundles are sold whole, and running short mid-job can leave you with mismatched lots. Many roofers also keep a spare bundle for future repairs.
Add up the length of the main ridge plus every hip line running from the ridge down to the eaves. All of these are capped with ridge shingles, so they all count toward the ridge length entered here.
No. It only calculates field shingle bundles and ridge cap bundles. Starter strips, underlayment, and flashing should be added separately according to your product instructions.
Multiply the squares figure shown in the calculator by four yourself, since the tool uses the common three-bundle ratio. Always trust the coverage printed on the package.