Contractor & construction
Construction Cost Calculator
Builds a construction cost, where the allowances and exclusions decide the final figure.
Result
Cost per square foot varies enormously by region, finish level and site conditions. Use local recent figures rather than national averages, and treat this as a budget range rather than an estimate.
Get a Free Business AuditHow the calculation works
Material, labour at burdened rates, equipment, subcontractors, permits and inspection fees, plus overhead and profit. The figure that matters as much as the total is what the estimate excludes, since the items discovered after the price was set are what consume the margin.
What moves the number
- Scope definition and what is excluded.
- Permit and inspection fees by jurisdiction.
- Site conditions and access.
- Code requirements under the adopted edition.
Where this one goes wrong
Existing conditions are where construction estimates fail, because what is behind a wall or under a slab is unknown until it is opened and the code requirements that then apply can change the scope substantially. State what is assumed and what is excluded. Permit and inspection costs also vary enormously by jurisdiction and are frequently underestimated, along with the time they add to the schedule.
Before you quote
- State the assumptions about existing conditions explicitly.
- Price permits and inspections for the actual jurisdiction.
- List exclusions in the estimate, not just inclusions.
Where the rules come from
Questions
About this calculator
Why do construction estimates overrun?
Existing conditions, mostly. What is behind a wall or under a slab is unknown until it is opened, and the code requirements that then apply can change the scope substantially. Stating the assumptions is the only defence.
What should be excluded explicitly?
Anything dependent on what is found: structural remediation, code upgrades triggered by the work, hazardous material abatement, and utility work. Listing them as exclusions is clearer than a contingency that gets spent and argued about.
Do permits cost much?
Enough to matter and they vary enormously by jurisdiction, with the review time affecting the schedule as much as the fee affects the cost. Both belong in the estimate for the actual jurisdiction rather than a general allowance.
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How to use this calculator
- Project area (sq ft) (sq ft). Enter your own figure; the page starts at 1,800 sq ft.
- Cost per square foot ($). Enter your own figure; the page starts at $185.
- Contingency (%). Enter your own figure; the page starts at 10%.
- Permits, design and fees ($). Enter your own figure; the page starts at $12,000.
- Site work and demolition ($). Enter your own figure; the page starts at $9,000.
The result updates as you type, so you can try a figure, see what it does to total estimated cost, and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| Project area (sq ft) | 1,800 sq ft |
| Cost per square foot | $185 |
| Contingency | 10% |
| Permits, design and fees | $12,000 |
| Site work and demolition | $9,000 |
What comes out
| Result | Value |
|---|---|
| Total estimated cost main result | $389,400 |
| Build cost | $333,000 |
| Contingency | $35,400 |
| All-in cost per square foot | $216.33 |
A 1,800 sq ft project comes to $389,400 all in, $216.33 per square foot once fees, site work and contingency are included.
How sensitive the answer is
Holding everything else steady and changing only cost per square foot, this is what happens to total estimated cost. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Cost per square foot ($) | Total estimated cost |
|---|---|
| $93 | $207,240 |
| $139 | $298,320 |
| $185 example above | $389,400 |
| $278 | $573,540 |
| $370 | $755,700 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- Project area (sq ft) (sq ft)
- Measured in sq ft, starting at 1,800 sq ft.
- Cost per square foot ($)
- A money amount, starting at $185.
- Contingency (%)
- A percentage, between 0 and 50, starting at 10%.
- Permits, design and fees ($)
- A money amount, starting at $12,000.
- Site work and demolition ($)
- A money amount, starting at $9,000.
What the results tell you
| Result | What it is |
|---|---|
| Total estimated cost | The headline result. A money figure. |
| Build cost | A money figure. |
| Contingency | A money figure. |
| All-in cost per square foot | A money figure. |
Overhead is where these go wrong
Pricing and margin figures are only as good as the cost you put in. If your cost covers parts and wages but not the van, the insurance, the phone and the unbilled hours, the markup is paying for those before it becomes profit, and the margin you think you are making is not the one you are making.
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