Free Tool
Roof Square Footage Calculator: How Many Squares Is My Roof?
Every roof quote is built on one number: how many squares the roof is. If one roofer says 28 and another says 34 for the same house, somebody's math is off. Measure your walls, pick your pitch, and get your own count in a few seconds - no climbing required.
Interactive Tool
Roof Squares Calculator
Measure the outside walls of the house (or read them off your appraisal-district record), pick the pitch, and the calculator turns that footprint into roof surface area, squares and shingle bundles. Defaults are an example - replace them with your numbers.
Roof surface
1,977 sq ft
Roof squares
19.8
Squares with waste
21.7
Shingle bundles
66
52.0 ft × 34.0 ft footprint (with overhang) = 1,768 sq ft, × 1.118 pitch factor for 6/12 = 1,977 sq ft of roof, or 19.8 squares before waste.
This assumes one simple roof over a rectangular footprint. Dormers, valleys, porches and second-story sections add area and waste, so a roofer's measured number (or an aerial report) can run higher. Use it to sanity-check the square count on a quote, not to order materials.
How to measure your roof from the ground
You don't need to get on the roof. Measure the length and width of the house along the outside walls, or look up the building footprint on your county appraisal district record. Add the eave overhang (often 12 to 24 inches) and the calculator adds it to both sides.
For pitch, use the roof pitch calculator with a level and tape at a gable end or in the attic. Many single-story homes fall somewhere between 4/12 and 7/12.
What the numbers mean on a roofing quote
Quotes usually list squares including waste, so compare that figure with the highlighted “squares with waste” result. If a quote is far above your number, ask whether it includes a detached garage, porch roof or second layer of tear-off. If it is far below, check that it covers the whole roof and not just the damaged slopes.
Then put the quotes side by side with the roofing quote comparison calculator, which works out the price per square for each one.
Pitch factors used
Roof area = footprint × √(1 + (rise ÷ 12)²). That gives 1.054 at 4/12, 1.118 at 6/12, 1.202 at 8/12, 1.302 at 10/12 and 1.414 at 12/12. Complex roofs with hips, valleys and dormers measure larger than this simple model, so treat the result as a floor, not a ceiling.
Official roofing references
Building code sets the minimum slope for shingles, and IBHS research covers which roof materials stand up to Texas hail.
- International Residential Code 2021, Chapter 9: Roof Assemblies
Section R905.2.2: asphalt shingles only on slopes of 2:12 or more, with double underlayment from 2:12 up to 4:12. Free to read online.
- IBHS Roof 101
Insurance Institute for Business & Home Safety research on roof materials, hail and wind resistance.
- Texas Department of Insurance: roofing and insurance, know the law
Texas rules on roofing contracts, deductibles and what a contractor may not do on your claim.
Questions
What is a roofing square?
A square is 100 square feet of roof surface. Roofers price shingles, underlayment and labor by the square, so a 2,400 sq ft roof is 24 squares.
Why is my roof bigger than my house's square footage?
Two reasons: the roof hangs past the walls at the eaves, and a sloped surface is longer than the flat footprint under it. On a 6/12 pitch the roof is about 12% larger than the footprint; on 12/12 it is about 41% larger.
How much waste should I add for shingles?
Roofers commonly add around 10% for a simple gable roof and more for hip roofs, valleys and dormers, because shingles are cut at every edge. The calculator lets you change the allowance.
How many bundles of shingles are in a square?
Most asphalt shingles are packed three bundles to a square, but some heavier designer lines need four or five. The bundle count per square is printed on the wrapper.
Two roofers measured my roof differently. Which one is right?
Ask how each one measured - tape on the roof, an aerial report or a satellite tool. A few percent apart is normal; 10% or more means one of them is counting area that isn't there or missing some. Run your own estimate here as a check.