Short answer: a roofing square is 100 square feet of roof area. To estimate yours, take your home's footprint, add about 10 percent for overhangs, then multiply by a pitch factor of roughly 1.05 to 1.4 depending on steepness. A 2,400 square foot single story home usually lands around 30 to 34 squares.

Why living area is not roof area

Two things separate them. First, the roof extends past the walls at the eaves and rakes. Second, a sloped roof covers more surface than the flat footprint beneath it, and the steeper the pitch the bigger that difference.

A two story home confuses this further, because 2,400 square feet of living area over two floors is only about 1,200 square feet of footprint.

The rough method

  1. Find your footprint. Living area divided by number of stories, approximately.
  2. Add for overhang. Multiply by about 1.10.
  3. Apply a pitch factor. Roughly 1.05 for a low slope, 1.12 for a moderate 6/12, 1.20 for an 8/12, up to about 1.40 for very steep.
  4. Divide by 100 for squares.

Our cost calculator does this for you and converts it to a price range.

Waste factor

Material ordered always exceeds roof area, because shingles are cut at valleys, hips, rakes and penetrations. A simple gable roof may run 10 percent waste. A cut up roof with many valleys can run 15 to 20 percent. That is normal and it should be reflected in the estimate rather than hidden.

Why two estimates show different squares

Usually measurement method. Satellite and aerial measurement services are good but they can misread pitch, miss small planes or include structures that are not in scope. An on roof measurement with a tape and a pitch gauge is more accurate, particularly on complex roofs.

If one quote shows materially fewer squares than the others, ask how it was measured. We cover this in satellite versus in person measurement.

What this is good for

Sanity checking a quote. If you know you have roughly 30 squares and a quote prices 22, something is wrong. If it prices 45, that is also worth asking about.

What it is not good for is signing a contract. Ranges are planning tools. A real measurement is what a written estimate should be based on.

Get a measured written estimate free, or call (210) 245-4125.