Use cost per square foot as a scenario, not a substitute for scope
For comparing your own installed-cost assumptions across a measured area. Starting ranges are hypothetical examples from the project brief, not verified regional price benchmarks or promises of an attainable market price.
Formula and worked example
Selected rate = low + (high − low) × slider position/100. Planning total = area × selected rate. Material/labor/other shares divide that same total. Premium scenario = area × high × premium factor.
For a hypothetical 400 ft² slab, a $6–$14/ft² range has a $10 arithmetic midpoint. The midpoint planning total is $4,000. At 45% material and 40% labor allocation, those portions are $1,800 and $1,600, with $600 remaining for other/overhead. A 1.2 premium factor on the high assumption gives $6,720. These are user-defined planning figures, not surveyed regional costs.
Define exactly what your unit-cost range includes
A cost-per-square-foot figure is meaningful only with a defined scope. A garage slab can mean a concrete pour alone or a larger installed package that includes excavation, base, reinforcement and finishing. A room addition can include very different work depending on structure, finishes and services. A roof replacement may include tear-off and disposal or only new installation. Write down the scope before comparing unit rates.
The planner provides example ranges for those three scope names, but the values are not presented as collected market data. Choosing a scope changes the starting range; it does not fill in a specification or verify a regional price. Replace both ends with your actual quotes or documented assumptions and record what those numbers include. Otherwise, a polished spectrum can give a precise-looking total for an undefined job.
Match the area basis to the price basis
Enter the area to which the chosen installed rate applies. For a slab, that may be its footprint. For a roof, it may be sloped roof area rather than the building's floor area. For an addition, the agreed measurement basis may differ from another contractor's quote. Do not multiply a roof-surface unit price by floor area simply because both are expressed in square feet.
Use the visual takeoff tools to calculate the relevant geometric area where their assumptions fit the project. Keep net measured area separate from material purchase area with waste. The planner's installed-cost rate may already include a material allowance, so multiplying it by an inflated purchase area could apply the same allowance twice. Compare the definitions alongside the final total, not only the displayed dollars.
Read low, midpoint, high and premium correctly
The slider interpolates between your low and high assumptions. At zero percent it selects low; at one hundred percent it selects high. At fifty percent it selects their arithmetic midpoint. The interface deliberately labels that point as a midpoint instead of an average because the calculator has no set of local observations from which to compute a market average or typical project cost.
The premium scenario multiplies your high assumption by an editable factor and then by area. It is a separate sensitivity comparison rather than another point on the low-to-high slider. A factor of 1.2 means twenty percent above the entered high rate. It does not represent a researched premium-finish price or a guarantee that a client will accept the resulting amount.
Use local evidence rather than automatic region labels
The region or quote-label field is a note that can be included in the copied summary. Typing a city or state does not secretly apply a multiplier or make the range current for that location. Build the range from comparable supplier quotes, subcontractor bids or completed jobs, and note when those figures were gathered. A location name cannot correct an outdated or mismatched cost basis.
When comparing jobs, review size, access, specification, schedule and inclusions. A small project can have a higher installed unit cost because mobilization and fixed tasks are spread over fewer square feet. Large projects can have other constraints. Those effects belong in your assumptions or a detailed estimate; the planner does not invent regional or scale factors from the area input.
Allocate the total without adding it again
Material share and labor share are percentages of the selected planning total. The remaining percentage becomes other and overhead allocation. Material and labor shares together cannot exceed one hundred percent. These amounts partition the same total; they are not additional charges layered on top of area multiplied by unit cost. That distinction keeps the spectrum and cost breakdown mathematically consistent.
The shares are also user-defined. A forty-five percent material allocation is an example, not a researched cost ratio for every slab, roof or addition. Use your own cost records to decide whether the split is useful. If the installed rate includes contractor profit, some of the other allocation may represent that profit; this planner does not identify it automatically or calculate a separate job margin from the shares.
Move from a scenario to a detailed bid
Use the planner to discuss a range and test how area or scope assumptions change a total. Before issuing a bid, build the material, labor, equipment and overhead estimate that supports it. The takeoff tools connect measured quantities with entered costs and a target margin; the financial calculators help review profitability and collection timing. Those checks give the broad unit-cost scenario an actual business basis.
Copy the summary or prepare an estimate line when you want to preserve a planning figure in a document. Label it as a scenario or allowance where appropriate rather than presenting an unsupported range as a fixed contracted price. Review scope, exclusions and payment terms with the actual project information. A more detailed estimate can then replace the preliminary figure without hiding why the price changed.
Frequently asked questions
Are these verified prices for my city?
No. The initial ranges are hypothetical examples. Enter ranges supported by your own local quotes or completed jobs. A region label is a note and does not trigger a regional price adjustment.
Why is the center labeled midpoint instead of average?
It is the arithmetic halfway point between the two numbers you entered. The tool does not have a sample of local project prices from which to calculate an observed average.
Does the material breakdown add to the displayed total?
No. Material, labor and other shares divide the existing planning total. They are not added again. Use a detailed takeoff and cost estimate when you need to establish an actual bid margin.