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ADU Return Estimator

Weigh a backyard unit: what it could cost, what it could rent for, and how long your cash would take to come back.

Updated September 2026 · Rudy Flores

An accessory dwelling unit (ADU) is a second, smaller home on your lot. Enter your own cost and rent estimates to see monthly cash flow, the return on your cash and the rent needed to break even.

Zillow puts typical rent for Coronado (ZIP 92118) near $5,550 a month for a whole home, so the starting rent below is set at about 55% of that; a smaller backyard unit usually rents for less than a house or apartment of typical size. The project cost is a placeholder: get bids before you rely on any result.

Total project cost

A starting figure, not a bid: include design, permits, fees, construction and utility connections. Replace it with real quotes.

Share of the cost you finance

Enter 0 if you would pay cash.

Loan interest rate

A starting figure. Loans for a project like this are often priced differently from a purchase mortgage.

Loan term

Monthly rent you could charge

A starting figure, set well below the typical rent for a whole home. Replace it with what similar units near you actually rent for.

Vacancy and turnover

Insurance, upkeep and utilities you pay

Percent of the rent you collect.

Value the unit adds to the assessed value

California may reassess new construction. Ask the county assessor how a project would be treated.

Property tax rate

Rent increase per year

Want this as a personal plan?

Send this estimate to Rudy and he will follow up with a personalized version, no pressure.

Talk to a lender. Rates, loan programs and approvals come from lenders, not from websites or real estate agents. Talk to your own mortgage broker, or use our preferred lender, Rodrigo Ballon with CrossCountry Mortgage, at 858-735-0255. You are always free to choose any lender you like, and you can verify any lender’s license at nmlsconsumeraccess.org.

A planning model on your own estimates. Rules, fees and rents vary by city and address. Nothing here is a loan offer, a rate quote, tax or legal advice. Rates shown come from public data and change often.

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ADU Return Estimator

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