Roofing Squares
Free Roofing Squares calculator with clear step-by-step results.
About Roofing Squares
A roofing square is 100 square feet, or 9.29 square metres, and is the unit roofing materials are quoted in across North America. Plan area is converted to sloped area using the rise-in-twelve pitch, then divided into squares and used to size underlayment and fixings.
Formulas
Sloped area
Sloped = plan area x square root of (1 + (rise / 12)^2)
Squares
Squares = sloped area m2 / 9.2903
Worked example
With the default values below, Roofing Squares returns Roofing squares of 13.24. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Roof plan areaminimum 0.5 m2
- 110 m2
- Pitch as rise in 12accepts 0–24 in 12
- 6 in 12
- Coverage per underlayment rollminimum 1 m2
- 37 m2
- Nails per roofing squareminimum 0 kg
- 1.1 kg
Results
- Roofing squares
- 13.24 squares
- Sloped roof area
- 122.98 m2
- Underlayment rolls
- 4 rolls
- Nails required
- 14.56 kg
Step by step
- 1Values used
- 2Sloped area
- 3Squares
- 4Roofing squares= 13.24 squares
- 5Sloped roof area= 122.98 m2
- 6Underlayment rolls= 4 rolls
- 7Nails required= 14.56 kg
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why 9.2903 square metres?
One roofing square is 100 square feet, and one square foot is 0.092903 square metres. The conversion is exact rather than rounded.
Does underlayment need the same waste allowance as shingles?
Less. Underlayment runs in long courses with modest laps, so ordering to the sloped area plus one roll is usually sufficient.