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Square Feet to Roofing Squares Calculator

Convert a measured roof area into squares — the unit roofers quote and suppliers sell in.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Roofing squares

20 squares

High confidence

1 square = 100 sq ft, so square feet ÷ 100 gives squares. Round up for ordering, but keep the exact figure when comparing per-square quotes.

Conversion factor applied
0.01 squares per sq ft

Once a roof has been measured, converting to squares is what lets the number be priced, because every supplier catalogue and every roofing quote is denominated that way. Dividing by a hundred is trivial; the judgement is in what area you divide. The figure must be sloped surface area, obtained either by measuring along the rafter line or by applying a pitch multiplier to the plan area. Round up for ordering, since bundles and underlayment rolls do not come in fractions, but keep the unrounded figure when comparing quotes priced per square — the difference between 21.4 and 22 squares is real money on a large roof, and a contractor will be pricing the former.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • A roofing square is 100 square feet of roof surface area

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

Do I round up to whole squares?
For ordering, yes — materials are sold in bundles and rolls, not fractions of a square. Keep the exact figure for comparing quotes, since a contractor pricing per square will use the precise area rather than the rounded one.
Should I subtract skylights and chimneys?
Only if they are substantial. Small penetrations are usually left in the area because the cut material around them is wasted anyway, and the labour of working around an opening exceeds the material it saves.
How do I get sloped area from a plan measurement?
Multiply plan area by the pitch multiplier, which is the secant of the roof angle. A four-in-twelve roof multiplies by about 1.054, a nine-in-twelve by about 1.25. Convert the pitch to an angle first if you only have the ratio.