How many squares is my roof?

Updated October 28, 2026 · QuickRoofBids

A roofing square is 100 square feet of roof surface. To find your roof’s squares, measure the pitched surface area of every roof plane, add them up and divide by 100. Most single-family homes in East Tennessee land between 15 and 35 squares. Contractors then add a waste allowance before pricing, so the number on a quote is always a little higher than the roof itself.

Why your house’s square footage is not your roof’s size

Homeowners usually know the heated square footage of their house, but a roof is bigger than the floor beneath it for two reasons. First, the roof extends past the walls: eaves and rake overhangs commonly add one to two feet on every side. Second, the roof is sloped, and a sloped surface covers more area than the flat footprint under it. The steeper the pitch, the bigger the gap. That is why two houses with the same 1,800 sq ft floor plan can need very different amounts of material, and why a quote that is calculated only from your listing’s square footage can be off by several squares in either direction. A second story changes things again: a two-story house with the same floor area has roughly half the footprint, and so a much smaller roof.

How pitch changes the number of squares

Roof pitch is written as rise over a 12-inch run, so a 6/12 roof rises six inches for every foot it runs horizontally. The pitch factor turns flat footprint into true surface area. The table below applies it to an 1,800 sq ft roof footprint (walls plus overhangs) before any waste is added.

Measuring your roof squares step by step

1. Split the roof into its flat planes (facets): each rectangle, triangle or trapezoid between ridges, hips and valleys.
2. Measure each plane along its slope, not along the ground, and calculate its area.
3. Add every plane together for the total roof surface in square feet.
4. Divide by 100 to get squares.
5. Add a waste allowance (we use 12%) to get the squares a contractor will actually order and price.

Climbing a roof with a tape measure is dangerous and rarely necessary. Our instant estimate does these steps from current aerial imagery, tracing each facet and its pitch, and gives you the measured area and squares together with your price range. It reads each facet’s slope from elevation data, so a steep front gable and a shallow back porch roof are each counted at their own pitch instead of one average for the whole house. It also measures only the building at your address, so a detached garage or a neighbor’s attached unit does not inflate your squares. When the aerial data for an address is not reliable enough to trust, the tool asks you to trace the roof outline yourself rather than guessing. See how the measurement works.

From squares to price

Once you know the squares, the price is close to a multiplication. At current East Tennessee rates, architectural shingles run $585 per square, 3-tab shingles $455 and metal $1,150. A 25-square roof (after waste) in architectural shingles is therefore roughly 25 × $585 before any adjustment for stories. The roof replacement cost guide walks through the full calculation with worked examples by roof size.