Free shingle calculator estimates shingle bundles, underlayment rolls and nails from roof footprint and pitch, with squares and project cost.
This calculator sizes an asphalt shingle roof - the complete material list for a shingle re-roofing job: shingle bundles, underlayment felt rolls and nails. Roofing is sold in squares and bundles rather than square meters: one roofing square is 100 square feet (9.29 m²) of roof surface, and asphalt shingles come about 3 to 4 bundles per square. This tool converts your metric measurements into the imperial roofing units suppliers use.
Enter the ground footprint of your roof, pick the closest pitch if you don't know the exact value (adjacent steps differ by only a few percent of area), choose the shingle type and set a waste allowance. The result gives the actual roof area, roofing squares, shingle bundles, underlayment rolls and nails, plus a cost estimate. Note: this calculator covers asphalt shingle roofs; metal roofs, clay tiles and flat-roof membrane systems follow different rules.
A roofing square is the industry unit equal to 100 square feet (about 9.29 m²) of roof surface. Shingles are sold by the bundle and priced per square. Using squares keeps estimates consistent between contractors and suppliers regardless of metric or imperial measurements.
Standard 3-tab shingles take 3 bundles per square (each bundle covers about 33.3 sq ft), while architectural shingles take 4 bundles per square (about 25 sq ft each). Select the right type in the calculator and it applies the correct rate automatically.
A steeper roof has more surface area than its ground footprint. A 3/12 pitch (about 14°) adds about 3% area, 6/12 (about 27°) adds about 12%, 9/12 (about 37°) about 25% and 12/12 (45°) about 41%. The calculator applies these pitch factors to your footprint area automatically.
Three quick ways: 1) Check the house blueprints or the original roof specification - pitch is often listed there. 2) Measure it: hold a level along a rafter or under the eaves, measure 30 cm along the level, then measure the vertical drop to the roof surface - a 15 cm drop over 30 cm is a 50% slope, about 27°, i.e. 6/12. 3) Use a digital angle gauge or a smartphone inclinometer app; most apps show degrees: about 14° = 3/12, 27° = 6/12, 37° = 9/12, 45° = 12/12. When in doubt pick the lower option - adjacent steps differ by only a few percent of area.
Look at the shingles from the ground or in a photo: 3-tab shingles are flat with a repeating pattern of three equal tabs separated by visible notches. Architectural (dimensional) shingles are thicker with a textured, staggered, layered look and no notches, which creates deeper shadow lines. If you still can't tell, check the original roofing receipt or warranty, or ask a roofer - the supplier quote may also say 'architectural' or 'dimensional'. When in doubt, match the bundles per square in your quote: 3-tab uses 3, architectural uses 4.