How ProjectCostWise calculates costs

What the complexity setting changes

The estimator applies one of four multipliers to the low and high calculations. The multiplier is visible in the estimator so the homeowner can choose the scope that best reflects the job.

• Simple: 0.90×
• Standard: 1.00×
• Complex: 1.20×
• High-detail / difficult access: 1.40×

Selected starting assumptions (full 16-category table linked below)

These are the default planning assumptions currently used by the ProjectCostWise estimator. They were selected internally as editable planning examples. No external contractor-bid sample or regional price data was used to calibrate them, and they should not be interpreted as live contractor bids, local averages or a guarantee of pricing.

• Kitchen remodel: $150–$300 per sq ft; default example 200 sq ft.
• Bathroom remodel: $120–$250 per sq ft; default example 80 sq ft.
• Roof replacement: $5.50–$11 per sq ft; default example 2,000 sq ft.
• Flooring installation: $4.50–$10 per sq ft; default example 1,000 sq ft.
• Interior painting: $1.80–$3.20 per sq ft; default example 1,000 sq ft.
• Deck build or replacement: $25–$60 per sq ft; default example 300 sq ft.
• Basement finish or remodel: $50–$150 per sq ft; default example 1,000 sq ft.
• Room or home addition: $150–$350 per sq ft; default example 300 sq ft.

Worked example: a 200 sq ft kitchen remodel

For a standard-complexity kitchen using the current default assumptions, the low side is 200 × $150 × 1.00 = $30,000. The high side is 200 × $300 × 1.00 = $60,000. Choosing a different complexity multiplier or editing the rates changes the range immediately.

What ZIP code does — and does not do

ProjectCostWise currently asks for a five-digit U.S. ZIP code because location matters to project context and contractor matching. The ZIP code does not currently apply an automatic regional price multiplier to the estimate. The displayed planning range is driven by the selected project type, project area, editable rates and complexity multiplier.

Where the numbers come from

The values above are ProjectCostWise starting assumptions used to create transparent planning ranges. They are not presented as a live nationwide contractor-price database, government index, appraisal or promise of what a contractor will charge. Local labor, material selection, permit requirements, site access, demolition, hidden conditions and contractor scope can all move a real bid materially above or below a planning range.

For all 16 documented categories, see the 2026 Estimator Planning Assumptions and downloadable CSV. Those rates were selected internally as editable examples, not derived from a documented sample of contractor bids. They should not be used as market averages.

As ProjectCostWise collects enough reliable, anonymized project and quote data, we intend to use that information to improve published planning guidance. Any future data-based benchmarks should be clearly labeled so users can distinguish observed data from editable planning assumptions.

How homeowners should use the result

• Use the range to test whether the desired scope and available budget are in the same general neighborhood.
• Adjust the editable rates when you already have better local information.
• Compare contractor bids line by line rather than assuming every proposal includes the same scope.
• Expect hidden conditions, permit requirements and material choices to change final pricing.
• Treat an onsite contractor proposal as more authoritative for a specific property than a planning calculator.

Editorial and update policy

We aim to keep estimator assumptions, cost-guide examples and this methodology page consistent with one another. When a default estimator assumption changes, the related guide should be reviewed so the published example does not contradict the calculator. Pages are also reviewed for technical SEO, crawlability, structured data and clear disclosure of limitations. See About ProjectCostWise & Editorial Standards for our broader publishing, corrections and monetization disclosures.

Last methodology clarification: October 1, 2026.

Frequently asked questions