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Roofing Squares Calculator

Find roofing squares and bundles.

How it is calculated

Roofers sell shingles by the square, the amount that covers 100 square feet, which is 9.2903 m². The tool divides your roof area (in m²) by that constant: squares = area / 9.2903. It then estimates bundles with bundles = ceil(squares × 3 × 1.1): three bundles per square, a 10% allowance for waste, cuts and starter courses, rounded up to a whole bundle. Squares are shown with two decimals. Enter the true sloped roof surface, not the floor plan; a steep roof has more surface than the footprint under it. The 3-bundles-per-square figure is common for standard shingles, but check the product label.

Worked example

Suppose the sloped roof surface is 150 m². Squares: 150 / 9.2903 = 16.15 (rounded from 16.146). Bundles before rounding: 16.146 × 3 × 1.1 = 53.28. Because you cannot buy part of a bundle, it is rounded up to 54. So order about 16.15 squares of coverage, which means 54 bundles including the waste allowance.

Try this example →

Common mistakes

  • Entering the footprint of the house instead of the sloped roof area, which underestimates the shingles.
  • Typing square feet into a field that expects square metres; 1 square is 100 sq ft or 9.29 m².
  • Treating squares as the number of bundles to buy; most shingles need roughly 3 bundles per square.
  • Skipping extra for ridges, valleys and hips, which waste more material than a plain gable.

About this calculator

This calculator converts a roof's area into roofing squares — the trade's standard unit, where one square equals 100 square feet — and then estimates how many shingle bundles that requires, typically three bundles per square for standard architectural shingles.

Roofing contractors and estimators use squares to quote jobs and order materials in the units suppliers actually sell them in, and homeowners use it to sanity-check a quote or plan a DIY reroofing project.

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  • Editorial team

    This tool takes the roof surface directly, so you must convert the floor plan yourself. For a 6 in 12 pitch, multiply the footprint by about 1.118, since the slope length is the square root of 1 plus 0.5 squared. A 120 m² footprint then becomes roughly 134 m² of roof, before any overhang. Tell us your roof's pitch and shape and how you estimated the area.

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