What an ADU Costs and Rents For in the Bay Area

A new 1-bedroom asks a median of $3,300 a month in Santa Clara County and $4,284 in San Francisco, across 89 listings for units built in 2021 or later that A-du read on October 30, 2026. On the cost side, Bay Area owners reported a median construction cost of $177,500, about $329 per square foot, the highest of any region in UC Berkeley’s statewide ADU survey.

However, three limits apply before you use any of these numbers. The rents are asking rents for new units, and 73% of them are apartments rather than ADUs. The neighborhood medians rest on two or three listings each, and the page shows how many next to every figure. And the build cost is from projects finished in 2018 and 2019, before the price rises since, so it is a floor rather than a quote.

What a new unit rents for in Santa Clara County

Across 52 listings in 11 neighborhoods, a new studio asked a median of $2,957, a 1 bedroom $3,300 and a 2 bedroom $4,494. The spread between neighborhoods is wide: Mountain View and south Palo Alto ask well over $4,000 for a 1 bedroom, while most of San Jose sits between $3,250 and $3,400.

What a new unit rents for in San Francisco

Across 37 listings in 7 neighborhoods, a new 1 bedroom asked a median of $4,284 and a 2 bedroom $6,159. The citywide studio median of $4,341 is pulled up by new SoMa and Dogpatch buildings, which is why it sits above the 1 bedroom figure. Several neighborhoods have too few new studios to publish a median at all.

Read these as the rent a new, private unit competes with, not as an appraisal of any one ADU. An ADU’s rent moves with its size, its own entrance and outdoor space, parking, and whether utilities are included. 13 of the 89 listings were themselves ADUs or backyard cottages. For a specific address, a plan page on A-du Build gives a rent estimate once you set your location.

What it costs to build

The one Bay Area build cost a reader can trace to owners themselves is from UC Berkeley’s Center for Community Innovation, which surveyed California owners of ADUs permitted or finished in 2018 and 2019. Bay Area owners reported the highest costs in the state:

Two things to adjust for. Building costs have kept rising since the survey: Turner’s national building cost index was up 5.49% in the year to the third quarter of 2026 alone. And the survey blends garage conversions with new detached units, which cost more. When you compare a quote against these figures, check whether it includes design, permit and impact fees and utility connections. For a lower-cost route, several Bay Area cities publish pre-approved ADU plans free of charge, including Oakland, San Ramon and Los Altos, and each plan page shows an estimated cost range for that design.

Working out return on cost

Return on cost is a year’s rent, less vacancy and operating costs, divided by what the unit cost to build. It leaves out the land, which an owner adding an ADU already has. A-du uses these operating assumptions on its Build plan pages: 5% vacancy, 8% management, 5% upkeep, $1,000 a year insurance, and property tax of 1.2% on the build cost.

A worked example, not a Bay Area figure: a 1 bedroom renting at the Santa Clara County median of $3,300 brings in $39,600 a year. At an all-in cost of $300,000, the net is about $27,872, a return of 9.3%. At $400,000, the net is about $26,672 and the return 6.7%. In this example, $100,000 of build cost moves the return by more than two points, which is why the cost side deserves as much attention as the rent.

For a real number, open a plan on A-du Build and set your address: the page computes return on cost from that plan’s cost range and a rent estimate for your location.

Where San Francisco permits ADUs

1,739 building permits whose description names an ADU were issued in San Francisco from January 1, 2020 through August 14, 2026. The ten neighborhoods with the most:

Common questions

How much does it cost to build an ADU in the Bay Area?

The most recent owner-reported figure from a public survey is UC Berkeley's: a median construction cost of $177,500, or about $329 per square foot, for Bay Area ADUs permitted or finished in 2018 and 2019. That was the highest of any region in the survey, against $100,000 in Los Angeles County. Building costs have kept rising since (Turner's national building cost index was up 5.49% in the year to the third quarter of 2026), so treat the survey as a floor. It is construction cost as owners reported it, and a new detached unit typically costs more than a garage conversion.

What does a new 1-bedroom rent for in San Jose and Santa Clara County?

Across 21 asking rents for 1-bedroom units built in 2021 or later in 11 Santa Clara County neighborhoods, read October 30, 2026, the median was $3,300 a month. Neighborhood medians ran from about $3,250 in South San Jose to over $5,000 in south Palo Alto. Most comps are new apartments rather than ADUs, so an ADU's rent will move with its size, privacy and parking.

What does a new 1-bedroom rent for in San Francisco?

Across 16 asking rents for 1-bedroom units built in 2021 or later in 7 San Francisco neighborhoods, read October 30, 2026, the median was $4,284 a month, from about $3,700 in the Outer Sunset and Outer Richmond to almost $6,000 in SoMa and Mission Bay.

What return on cost can a Bay Area ADU earn?

It depends almost entirely on what the unit costs to build and what it rents for, so there is no one Bay Area figure. As a worked example with A-du's published operating assumptions (5% vacancy, 8% management, 5% upkeep, $1,000 a year insurance and 1.2% property tax on the build cost, land left out): a 1-bedroom renting at the Santa Clara County median of $3,300 returns about 9.3% a year on a $300,000 all-in cost and about 6.7% on $400,000. A-du's Build plan pages compute it for a specific plan and address.

How many ADUs has San Francisco permitted?

1,739 building permits whose description names an ADU were issued in San Francisco from January 1, 2020 through August 14, 2026, by A-du's count of the city's DBI permit records. The most were in Sunset/Parkside (173), Mission (154), Bayview Hunters Point (110). These are issued permits, not completed units.

Where does this data come from?

The rents are asking rents A-du read from public listing pages on October 30, 2026, for units built in 2021 or later, 89 in all. The build cost is UC Berkeley's 2020 statewide ADU owner survey. The San Francisco permit count is from DataSF's building permit records. A median is published only where an area and unit type has at least 2 comps, and sample sizes are shown next to every figure.

Method, and what is left out

Rents. On October 30, 2026, A-du read asking rents from public listing pages for studio, 1 bedroom and 2 bedroom units built in 2021 or later, in named neighborhoods of Santa Clara County and San Francisco. A unit was included only where the page itself stated a build year of 2021 or later. Where a floor plan showed a range, the low end was used. Townhomes and ADUs were sought first, then small buildings, then larger apartment buildings. Where a neighborhood had too few, comps from an adjacent ZIP were used and are marked. A median is published only where an area and unit type has at least 2 listings. Listing addresses and links are not published; the aggregates are in the CSV download.

Build cost. The regional medians are reproduced from UC Berkeley’s survey as published. A-du does not adjust them, and does not publish a modeled current cost.

San Francisco permits. Distinct permit numbers in the San Francisco Department of Building Inspection’s building permit records on DataSF, issued on or after January 1, 2020, whose description mentions an ADU, a JADU or an accessory dwelling, matched on whole words. Counted by the city’s analysis neighborhood. A permit can cover more than one unit, and some permits are revisions to an earlier one, so this is a count of permits, not of homes.

These figures are free to republish with credit to A-du, as set out on the press page. For Los Angeles, see what an ADU costs in Los Angeles, built from every finaled city permit.