FranklyA 'square' is 100 square feet, and that is how roofers price
Roofing is quoted in squares. One square equals 100 square feet of roof surface — not floor area. A 2,000 square foot single-storey house with a moderate pitch usually has well over 2,000 square feet of roof once pitch, overhangs, and hips are counted, so dividing a quote by the house's living area gives a per-square-foot figure that is too high. Ask the contractor how many squares they measured. If two estimates disagree on the square count before they disagree on price, that is the first thing to resolve.
Convert any estimate into a comparable number
Take the total price, subtract any separately listed items that are not roofing — solar detach and reset, gutters, skylights, stucco repair — then divide by the measured square footage of the roof. That gives you a per-square-foot figure for the roofing work itself. Do the same arithmetic on every bid. Most of the time the spread narrows sharply, and what is left is a real difference in scope rather than a difference in price.
What legitimately moves the price per square foot
Material system (composition shingle, concrete or clay tile, single-ply or modified bitumen on low slope), number of existing layers to tear off, pitch, number of storeys, access for material staging and a dump trailer, the count of valleys, chimneys, skylights, and pipe penetrations, flashing replacement versus reuse, ventilation changes, and whether the deck needs new sheathing. Each of these is a real cost. Each should appear as a line you can read, not as an unexplained round number.
What is usually missing from a low per-square-foot price
Cheap quotes are rarely cheaper labour — they are smaller scope. The items that quietly disappear: replacing flashings instead of reusing them, the underlayment grade, new pipe boots, edge metal, disposal fees, the permit, and a written per-sheet price for replacement plywood. A quote that says nothing about decking is not including it; it is deferring the conversation until the roof is open and you have no leverage.
Why published price ranges rarely settle the question
National cost-per-square-foot averages fold together tear-offs and overlays, one-storey and three-storey, shingle and tile, coastal and inland. A Southern California tile lift-and-relay and an inland composition tear-off are not comparable jobs, and an average that contains both tells you very little about the paper in front of you. The useful test is not whether the price matches a published number — it is whether the scope matches the roof.
Questions that make the number explainable
How many squares did you measure, and how? How many layers are being removed? Which flashings are being replaced rather than reused? What is the underlayment product and weight? What is the per-sheet price if decking needs replacing? Is the permit included? Is disposal included? A contractor who answers those in writing has given you a price you can actually check.