Why renovation cost per square foot misleads
Two jobs of identical area can differ five times in cost. Area is a comparison unit, not an estimating one.
The short answer
Cost per square foot is an output of an estimate, not an input to one. Renovation cost is driven by the number of serviced rooms, fixtures and trades involved rather than by floor area, so two projects of the same size routinely differ by several times.
The formula
cost = sum of (room or element cost) + services + finishes + general conditions
cost per sq ft = total cost / area (calculate last, never first)
useful comparison = cost per serviced room, or per fixture
The direction matters. Multiplying an area by a rate you found online produces a number with no relationship to your job; dividing your real estimate by the area produces a benchmark you can use next time.
Worked example
Two refurbishments, both 1,200 square feet:
Job A: paint throughout, new flooring, minor repairs
= 33,600 total → 28.00 per sq ft
Job B: same area, plus a kitchen and two bathrooms
kitchen 42,000 · bathrooms 2 x 18,000 = 36,000
rest of the space 30,000 · services 18,000
= 126,000 total → 105.00 per sq ft
Identical area, 3.75 times the cost. Nothing about the square footage predicted it, because the money is in the kitchen, the bathrooms and the pipework, not in the floor.
What actually drives the number
Water and waste. A room that needs plumbing costs several times a room that does not, and moving a soil stack costs more than the room it serves.
Fixture count and quality. Two bathrooms is not one bathroom scaled up; it is two of nearly everything. And the spread between a builders-grade and a mid-range specification on the same layout can be double.
Trade count. Every additional trade adds coordination, a mobilisation, and a dependency that can stall the programme. A job with three trades runs; a job with nine needs managing.
Condition, which nobody can see from a floor plan. A sound property and a damp one of the same size are different projects.
Where the published figures come from
Most per-square-foot ranges you find are averages across enormous samples, spanning different regions, specifications and property ages. An average that runs from $20 to $200 is arithmetically true and useless for a decision.
They are also usually quoted without saying whether they include design fees, permits, appliances or the general conditions of running the site, and those can be a fifth of the job.
A better way to sanity-check a budget
Price by element and let the per-square-foot number fall out at the end. Kitchen, each bathroom, the rest of the floor area, then services, then general conditions as a percentage.
Keep your own figures once you have done a few. Your cost per bathroom in your market with your subcontractors is worth more than any national average, and after three or four jobs you will have it.
If someone insists on a per-square-foot figure early, give a range and say plainly what would move it to either end. That is honest and it is more useful than a single number that will be quoted back at you in month three.
What this leaves out
- Figures are illustrative and regional. Labor rates and material costs differ enough between markets to change every number here.
- Excludes structural work, planning and permits, which are priced separately and vary with jurisdiction.
- Assumes an occupied-standard refurbishment, not a shell conversion, where the drivers are different again.
Common questions
- Is there a reliable cost per square foot for renovation?
- Not one that survives contact with a specific job. The figure is useful for comparing your own completed projects to each other, and for spotting when a quote is wildly out of line, but it cannot generate an estimate.
- Why do contractors quote so differently for the same job?
- Usually because they are not quoting the same job. Different assumptions about specification, what is included, and what happens if the floor comes up rotten. Comparing quotes only works when the scope has been written down first.
- How much should I budget for a kitchen?
- Price it as its own project rather than as part of a floor area. Units, worktop, appliances, plumbing, electrics and making good are each real numbers, and the total is what should feed your overall budget.
Spreadsheets that do this
The formulas above, already built and checked — so you fill in your numbers rather than the arithmetic.
Related guides
Last reviewed 22 August 2026