Roofing is quoted in squares and sold in bundles, and the two are not the same thing. Worse, the roof is bigger than the house — a 4 in 12 pitch adds about 5% to the area, and a 12 in 12 pitch adds over 40%. This handles both, and lists what the square count leaves out.
Enter the footprint and the pitch, not the sloped measurement. We'll work out the real roof area, the bundles to order, and the underlayment, drip edge and ridge cap that come on a separate line.
Works in metric and US imperial — you choose at the start and can switch at any time. Every figure this calculator uses is published with its source, and the result comes with a printable order sheet. No account, no email, and nothing you type leaves your browser.
Related: Siding calculator · Stud calculator · Gravel calculator
All calculators · How to use them · The standards behind our figures
Roofing is quoted in squares and sold in bundles, and they are not the same thing. A square is 100 sq ft (9.29 m²) and is not something you can buy — bundles are, at three to the square for three-tab and most architectural shingles, though heavier products differ. And the roof is always bigger than the footprint: a 4 in 12 pitch adds about 5% to the area, a 12 in 12 adds 41%. Enter the footprint and the pitch, not a sloped measurement.
Most codes allow a maximum of two layers total. If there are already two, you are paying for a full tear-off whether you budgeted for one or not — and that changes the job substantially. Budget for the skip before the shingles: a tear-off generates roughly 1 to 1.4 tonnes of heavy waste per 10 squares for a single layer of asphalt, and skip hire is not a rounding error on a domestic roof.
Do not lay shingles cold. Below about 5 °C / 40 °F the self-seal strips will not bond until the weather warms, and until they do the roof is vulnerable to wind lift. Allow roughly 320 nails to the square for four-nail fixing, more in a high-wind zone where six is often required — they are cheap, and running out mid-slope on a hot day is not. Order it all in one batch, because shingle colour drifts between production runs and a roof is the one surface nobody can avoid seeing from the street.
100 square feet, or 9.29 m2. It is a unit of area rather than something you can buy — shingles come in bundles, usually three bundles to the square for three-tab and most architectural products, though heavier ones differ.
About 5% at a 4 in 12 pitch, and 41% at 12 in 12. That is why you enter the footprint and the pitch rather than trying to measure the slope: the roof is always bigger than the house underneath it.
Most codes allow a maximum of two in total. If there are already two up there, the job includes a full tear-off, which changes both the cost and the waste disposal substantially.
Not below about 5 degrees C / 40 F. The self-seal strips will not bond until the weather warms, and until they do the roof is vulnerable to wind lift.