Roofing squares and waste calculator

Turn a roof footprint and pitch into roof area, roofing squares and shingle bundles, with a waste allowance added on.

How it works

A sloped roof has more surface than the ground it covers. The pitch factor is the square root of 1 plus the pitch over 12, squared. A 6 in 12 roof has a factor of about 1.118.

Roof area is the footprint times the pitch factor, shown to the whole square foot.

The waste allowance is added on top for cuts, hips, valleys and starter rows. One square is 100 square feet of roof.

Most shingles come three bundles to a square, so bundles are squares times 3, rounded up to a whole bundle. Bundles are worked from the unrounded squares, so they can differ a little from the squares shown times 3. Check the count on the shingles you buy, and measure the roof before ordering.

Want to price whole roofing jobs, in a spreadsheet? Roofing Estimate Calculator with Waste and Markup, Excel, $24.

This is arithmetic on the numbers you enter. It is not tax, legal or financial advice.