Free Tools

ADU tools & calculators

Eleven free tools that turn ADU questions into real answers — feasibility, your city's rules, cost and financing math, a personalized plan you can print, and a contractor bid comparator. Every one is free, runs in your browser, and asks for nothing. They're grouped by where you are in the process, from "is this even possible?" to "which contractor do I trust?"

Start here — is an ADU right for my property?

Free, instant, and nothing to sign up for. Get oriented before you spend a dollar.

ADU Cost Estimator Size × type × finish → a planning cost range and monthly payment. Interactive30 sec ADU Feasibility Check 14 questions → an honest read on your ADU path and what to check. Interactive2 min Which ADU Should You Build? 5 questions → the ADU type that fits your lot, budget and goals. Interactive60 sec California ADU Rules Explorer Pick your county and city — state minimums plus verified local programs and permit contacts. DatasetNo reload Size & Setback Calculator The minimum size, height and setbacks your city must allow under state law. CalculatorState law

Plan the project and the money

Turn a rough idea into real numbers you can budget and finance around.

Build My ADU Plan Answer once → a personalized, printable report: rules, cost, financing, timeline, next steps. Flagship5 steps Loan Payment Calculator Your monthly payment from your own loan amount, rate and term. CalculatorIllustrative Rental ROI Calculator Cash-on-cash return and payback from your build cost, rent and expenses. CalculatorIllustrative Property-Tax Estimator What an ADU actually adds to your tax bill — a partial reassessment, not a full reset. CalculatorProp 13 Fee-Exemption Checker Whether impact and school fees can legally apply at your ADU's size. CalculatorStatutory

Choosing and vetting a contractor

Where a homeowner is most exposed — and where an independent tool helps most.

Bid Comparator Enter 2–3 bids → true cost per square foot and which scope items each one leaves out. InteractiveNothing stored Contractor Red-Flags Checklist Interactive checklist of the warning signs worth taking seriously before you sign. ChecklistPre-signing

Prefer a person to look at your specific property?

A free property review checks your actual lot, city, and goals — and we'll tell you honestly if an ADU isn't a good fit yet.

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