This calculator vs. a flat price per house square foot
“$7 a square foot, done” is not a price for a reroof — it is a price for one pitch and one tear-off layer, quietly applied to every house that calls in with a different footprint.
What a flat price per house square foot is
A flat price per house square foot is the fastest way to quote a reroof over the phone: multiply the house's footprint square footage by a number and read it back. Customers shop it because it is easy to compare between bids, and it is the number a customer holding a competitor's quote will ask you to match.
The number behind it was set for one kind of roof — usually a simple, low-slope main with one covering layer to tear off — and then reused for every house afterward, whether or not the next one is steep, carries a second or third layer underneath, or adds a garage, porch, or dormer at a different pitch.
What this calculator is
This page keeps no account and sends nothing to a server. You enter each section's footprint and pitch, how many layers are coming off, waste, a material preset, install and tear-off hours, and your own wage, payroll burden, dump, permit, overhead, and target margin. It converts each section's footprint to actual roof surface using its pitch, prices material and labor by the square with a steep-labor multiplier, prices tear-off by the layer, and returns the job price, the price per square, the effective hourly rate, and the walk-away price — for this roof and this pitch, not a flat number for every house.
| What a flat price per house square foot does | What this calculator does instead |
|---|---|
| Charges the same fee whether a section is a flat 4/12 or a steep 12/12, even though the steeper section has 41% more actual roof surface on the identical footprint. | Converts each section's footprint to surface area with its own pitch factor (surface = footprint × √(1 + (rise/12)²)), then prices material and covers-per-square from the real surface, not the footprint. |
| Has no line for how steep a crew has to work — a 12/12 tear-off and install gets the same labor rate as a 4/12. | Applies a steep-labor multiplier by pitch (up to double the normal rate above a 12/12) to both install and tear-off hours, so a harder-to-walk roof costs more to crew. |
| Quotes the same number for a single-layer tear-off and a two- or three-layer tear-off, with no separate line for the extra strip-off and dump. | Prices tear-off surface as squares × layers, so a house with two layers of old shingles tears off, dumps, and bills for twice the material a single-layer house does. |
| Has no per-section breakdown — a steep garage or dormer eating a third of the labor on a fraction of the footprint disappears into one house-wide number. | Prices every section — main, garage, porch, dormer, addition — on its own footprint, pitch, and tear-off layers, and reports each section's share of total labor hours. |
| Gives the estimator a number to quote, not a number to check a quote against. | Reports the walk-away price and the price per square, so a shopped price can be scored against real cost before you commit to it. |
Two 2,200 sq ft footprints, one flat price
Using this calculator's own shipped starting example:
A 2,200 sq ft footprint — a 1,800 sq ft main house at a 6/12 pitch and a 400 sq ft attached garage at 4/12, both a single-layer tear-off — prices at $13,857.34 — $6.30 per footprint square foot — on a job that costs $11,085.87 to run.
Take the identical 2,200 sq ft footprint and make it a steeper roof instead — the main house at a 12/12 pitch and the garage at 10/12, both with a two-layer tear-off coming off first — and the job costs $19,652.96 to run before a dollar of profit, and this calculator prices it at $24,566.20: $11.17 per footprint square foot, 1.77 times the easy job's price, on the identical footprint. Quoting the steep job at the easy job's flat $13,857.34 price prices it $5,795.62 below its own break-even cost — before counting the $10,708.86 it falls short of this calculator's own price at a 20% target margin. Same footprint, same flat price, one roof that pays and one that loses money the moment the pitch and the tear-off layers show up.
Common questions
Why does a flat price per house square foot get a reroof wrong?
Because the cost driver is the roof's actual surface area and how many layers are coming off, not the house's footprint. A 1,800 sq ft main house at a 6/12 pitch has about 20.1 squares of roof surface, not 18; the same footprint at 12/12 has about 25.5 squares -- 41% more material and cutting for the identical footprint. Add a second tear-off layer and the crew is stripping twice the material before a single shingle goes down. A flat price per house square foot charges by the footprint because that is the only number it has, not because the footprint is what the job actually costs.
What does a flat price per house square foot usually leave out entirely?
Pitch and tear-off layers. A flat price has no line for a steep section's extra roof surface from the pitch factor, no line for the steep-labor multiplier a crew working a 12/12 actually needs versus a 6/12, and no separate line for a second or third tear-off layer, which doubles or triples the tear-off hours and dump weight on the same footprint. It also has no line that separates a low, simple main from a steep, multi-layer garage or dormer, since the flat number was set on the house's total footprint alone.
How big is the pricing gap in practice?
On this calculator's own shipped starting example: a 2,200 sq ft footprint -- a 1,800 sq ft main at a 6/12 pitch and a 400 sq ft attached garage at 4/12, both single-layer tear-off -- prices at $13,857.34, on a job that costs $11,085.87 to run: $6.30 per footprint square foot. Take the identical 2,200 sq ft footprint and make the main 12/12 and the garage 10/12, both with a two-layer tear-off, and the job costs $19,652.96 to run before a dollar of profit, and this calculator prices it at $24,566.20 -- $11.17 per footprint square foot, 1.77 times the easy job's price, on the identical footprint. Quoting the steep job at the easy job's flat $13,857.34 price prices it $5,795.62 below its own break-even cost, before counting the $10,708.86 it falls short of this calculator's own price at a 20% target margin. Same footprint, same flat price, one roof that pays and one that loses money the moment the pitch and the tear-off layers show up.
Is a flat price per house square foot ever the right way to quote?
For a narrow band of similar jobs -- a low-slope house with a single covering layer to tear off and no unusual sections -- a flat per-footprint-square-foot number can land close, because that is probably the job the price was set on. The risk is quoting a steep pitch, multiple tear-off layers, or a mix of sections (a main, a garage, a porch, a dormer) sight unseen, because the price does not know the pitch or the layer count until someone measures the roof, and by then the flat number has often already been quoted.
Does this calculator know my local labor rates or material costs?
No. It has no data on your local labor market, your supplier's pricing, or your material costs. It takes each section's footprint, pitch, and tear-off layers, a material preset, waste, install and tear-off hours, your own wage, burden, dump, permit, overhead, and target margin, and turns that into a price for this roof -- the arithmetic a flat price per house square foot skips, not a market survey.
Open the Roofing Bid Calculator to price your own reroof, or read the squares-by-pitch walkthrough.