How we calculate
Every number on CostBrick is a planning range, built from published data and a documented formula. This page explains exactly how — and how to correct us when we are wrong.
1. The formula
Most calculators combine four inputs:
low = quantity × base_low × factor × state_multiplier + add-ons high = quantity × base_high × factor × state_multiplier + add-ons final range = (low..high) + permit allowance (2%–8%)
Quantity is what you enter (sq ft, trees, systems). Base is the installed cost per unit for the system or material you pick. Factor adjusts for level (e.g., R-value). State multiplier adjusts for local labor rates. Add-ons are optional items (removal, air sealing, stump grinding) with their own published ranges.
2. Where the numbers come from
- U.S. Census Bureau — home size, ownership and regional construction activity (census.gov)
- Bureau of Labor Statistics — occupational wages for trades, used for state labor multipliers (bls.gov)
- U.S. Energy Information Administration — residential energy prices, used in energy-related ranges (eia.gov)
- U.S. Department of Energy — insulation R-value guidance and appliance standards (energy.gov)
- State energy offices and utility rebate programs — local incentive context
- Published contractor cost guides and manufacturer installation data — cross-checked ranges
Each calculator states its assumptions; if a range looks wrong for your area, tell us and we will re-check the source.
3. How often we update
Ranges are reviewed at least twice a year, and immediately when a source publishes a new figure (for example, annual tax or efficiency updates). Every calculator page shows a last updated date.
4. What our estimates are not
They are not bids, offers or guarantees. They do not include your specific site conditions, permit fees set by your county, or a contractor's overhead. A real quote requires an on-site assessment.
5. Independence and how we make money
CostBrick is free. We may receive a referral fee when a homeowner chooses to request local pricing. That fee never changes the estimate you see, and it does not obligate you to hire anyone. We do not sell advertising space inside the calculators.
6. Report an error
If a number is wrong, outdated or missing for your state, email support@costbrick.com or use the contact form (choose "Data correction"). We log every report, check the source, and publish the correction — including when we were wrong.