ADUByCity

Quarterly Index

California ADU Cost Index 2026

ADU build cost ranges ranked from lowest to highest across 100 California cities. Sourced from official planning data and contractor estimates. Updated Q1 2026.

Costs reflect the midpoint of reported build cost ranges. All figures are estimates — actual project costs vary based on site conditions, ADU type, and finish level.

State Low

$138k

avg midpoint

Median City

$235k

avg midpoint

State High

$475k

avg midpoint

Cost Bands: All 100 Cities Ranked

Cities divided into four cost quartiles from most affordable to most expensive.

Most Affordable (Bottom 25%)

Bakersfield(Kern)$85,000 – $190,000
Modesto(Stanislaus)$90,000 – $195,000
Fresno(Fresno)$90,000 – $200,000
Stockton(San Joaquin)$90,000 – $200,000
San Bernardino(San Bernardino)$100,000 – $220,000
Hemet(Riverside)$110,000 – $225,000
Fontana(San Bernardino)$110,000 – $230,000
Moreno Valley(Riverside)$110,000 – $230,000
Riverside(Riverside)$110,000 – $240,000
Hesperia(San Bernardino)$115,000 – $235,000
Ontario(San Bernardino)$115,000 – $240,000
Victorville(San Bernardino)$115,000 – $240,000
Redding(Shasta)$120,000 – $245,000
Lodi(San Joaquin)$120,000 – $245,000
Lancaster(Los Angeles)$120,000 – $250,000
Visalia(Tulare)$120,000 – $250,000
Clovis(Fresno)$120,000 – $250,000
Santa Ana(Orange)$120,000 – $260,000
Elk Grove(Sacramento)$120,000 – $260,000
Chico(Butte)$130,000 – $265,000
Rialto(San Bernardino)$130,000 – $265,000
Tracy(San Joaquin)$130,000 – $265,000
Palmdale(Los Angeles)$130,000 – $270,000
Jurupa Valley(Riverside)$130,000 – $270,000
Santa Maria(Santa Barbara)$135,000 – $275,000

Below Median (25–50%)

Menifee(Riverside)$135,000 – $275,000
Vacaville(Solano)$140,000 – $285,000
Citrus Heights(Sacramento)$140,000 – $285,000
Pomona(Los Angeles)$140,000 – $290,000
Compton(Los Angeles)$145,000 – $290,000
Anaheim(Orange)$140,000 – $300,000
Chula Vista(San Diego)$140,000 – $300,000
Fairfield(Solano)$145,000 – $295,000
El Monte(Los Angeles)$145,000 – $295,000
Murrieta(Riverside)$145,000 – $295,000
South Gate(Los Angeles)$145,000 – $295,000
Corona(Riverside)$145,000 – $300,000
Antioch(Contra Costa)$150,000 – $305,000
Temecula(Riverside)$150,000 – $305,000
West Covina(Los Angeles)$150,000 – $305,000
El Cajon(San Diego)$150,000 – $305,000
Norwalk(Los Angeles)$150,000 – $305,000
Vista(San Diego)$150,000 – $305,000
Rancho Cucamonga(San Bernardino)$150,000 – $310,000
Downey(Los Angeles)$150,000 – $310,000
Salinas(Monterey)$155,000 – $310,000
Roseville(Placer)$155,000 – $310,000
Simi Valley(Ventura)$155,000 – $310,000
Vallejo(Solano)$155,000 – $310,000
Santa Clarita(Los Angeles)$150,000 – $320,000

Above Median (50–75%)

Oxnard(Ventura)$150,000 – $320,000
Whittier(Los Angeles)$155,000 – $315,000
Alhambra(Los Angeles)$155,000 – $315,000
Palm Springs(Riverside)$155,000 – $315,000
Escondido(San Diego)$155,000 – $320,000
Ventura(Ventura)$160,000 – $325,000
Garden Grove(Orange)$160,000 – $330,000
Oceanside(San Diego)$160,000 – $330,000
Fullerton(Orange)$160,000 – $330,000
Richmond(Contra Costa)$160,000 – $330,000
Inglewood(Los Angeles)$160,000 – $330,000
Hawthorne(Los Angeles)$160,000 – $330,000
Petaluma(Sonoma)$165,000 – $330,000
Irvine(Orange)$160,000 – $340,000
Mission Viejo(Orange)$165,000 – $335,000
Westminster(Orange)$165,000 – $335,000
Lake Forest(Orange)$165,000 – $335,000
Orange(Orange)$165,000 – $340,000
Sacramento(Sacramento)$130,000 – $380,000
Concord(Contra Costa)$170,000 – $340,000
San Luis Obispo(San Luis Obispo)$170,000 – $345,000
Glendale(Los Angeles)$160,000 – $370,000
Santa Rosa(Sonoma)$170,000 – $360,000
Napa(Napa)$175,000 – $355,000
Torrance(Los Angeles)$175,000 – $360,000

Most Expensive (Top 25%)

Carlsbad(San Diego)$175,000 – $360,000
Costa Mesa(Orange)$175,000 – $360,000
Burbank(Los Angeles)$175,000 – $360,000
San Leandro(Alameda)$175,000 – $360,000
Livermore(Alameda)$180,000 – $365,000
Thousand Oaks(Ventura)$150,000 – $400,000
Huntington Beach(Orange)$175,000 – $380,000
Hayward(Alameda)$185,000 – $380,000
Long Beach(Los Angeles)$150,000 – $420,000
Santa Cruz(Santa Cruz)$195,000 – $395,000
Los Angeles(Los Angeles)$150,000 – $450,000
Santa Barbara(Santa Barbara)$200,000 – $400,000
Newport Beach(Orange)$200,000 – $410,000
Fremont(Alameda)$200,000 – $420,000
Daly City(San Mateo)$210,000 – $420,000
San Diego(San Diego)$160,000 – $480,000
Sunnyvale(Santa Clara)$220,000 – $430,000
Pasadena(Los Angeles)$170,000 – $480,000
Santa Clara(Santa Clara)$220,000 – $430,000
San Mateo(San Mateo)$220,000 – $430,000
Berkeley(Alameda)$230,000 – $450,000
San Jose(Santa Clara)$200,000 – $550,000
Oakland(Alameda)$200,000 – $550,000
Santa Monica(Los Angeles)$200,000 – $600,000
San Francisco(San Francisco)$250,000 – $700,000

By County

Average ADU Cost by County

Averaged across all tracked cities in each county. Sorted from lowest to highest.

Kern County(1 city)$138k avg
Stanislaus County(1 city)$143k avg
Fresno County(2 cities)$165k avg
San Joaquin County(3 cities)$175k avg
Shasta County(1 city)$183k avg
San Bernardino County(7 cities)$184k avg
Tulare County(1 city)$185k avg
Butte County(1 city)$198k avg
Riverside County(9 cities)$203k avg
Sacramento County(3 cities)$219k avg
Solano County(3 cities)$222k avg
Monterey County(1 city)$233k avg
Placer County(1 city)$233k avg
Contra Costa County(3 cities)$243k avg
Ventura County(4 cities)$246k avg
San Diego County(7 cities)$249k avg
Los Angeles County(21 cities)$250k avg
Orange County(12 cities)$250k avg
Santa Barbara County(2 cities)$253k avg
Sonoma County(2 cities)$256k avg
San Luis Obispo County(1 city)$258k avg
Napa County(1 city)$265k avg
Santa Cruz County(1 city)$295k avg
Alameda County(6 cities)$308k avg
San Mateo County(2 cities)$320k avg
Santa Clara County(3 cities)$342k avg
San Francisco County(1 city)$475k avg

What Drives ADU Cost

›

ADU type

Garage conversion: 30–50% cheaper than new detached build

›

Location (city)

Coastal metros can be 2x the cost of inland cities

›

Site conditions

Slope, poor soil, or old utilities add $10k–$50k+

›

Permit fees

$5k–$30k+ depending on city; waived under 750 sq ft

›

Finish level

Basic finishes vs. high-end can be a $50k–$100k+ difference

›

Utilities

Separate meter or sewer connection adds $5k–$25k

ADU Cost Questions Answered

How much does it cost to build an ADU in California in 2026?

ADU build costs in California range from approximately $80,000–$150,000 for a simple garage conversion to $400,000–$600,000+ for a custom detached ADU in a high-cost coastal city. The most common range for a new 600–800 sq ft detached ADU statewide is $180,000–$350,000.

Why do ADU costs vary so much between California cities?

The main drivers are: (1) local labor rates, which are significantly higher in the Bay Area and coastal LA than in the Inland Empire or Central Valley; (2) site conditions — sloped lots, poor soil, and existing infrastructure all add cost; (3) permit fees, which can range from $5,000 to $30,000+ depending on the city; and (4) finish level and ADU type.

Is a garage conversion cheaper than a new detached ADU?

Yes, generally by 30–50%. A garage conversion avoids foundation costs and may reuse the existing structure. Expect $80,000–$180,000 for a conversion vs. $180,000–$400,000+ for a new detached build. However, costs depend heavily on the existing garage condition, city requirements, and finish level.

What is the cost per square foot to build an ADU in California?

Statewide, ADU construction typically runs $250–$500 per square foot of finished space. Coastal cities like San Francisco, Santa Monica, and parts of Los Angeles trend toward $400–$600/sq ft. Inland cities like Fresno, Bakersfield, and Stockton typically run $200–$350/sq ft.

How do permit fees affect total ADU project cost?

Permit fees are a significant line item. In a city with $5,000–$10,000 in permit fees, they represent 3–5% of a typical project. In San Francisco where permit fees can exceed $30,000, they can represent 8–12% of total cost. ADUs under 750 sq ft qualify for state-mandated impact fee waivers, which can save an additional $5,000–$30,000.

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Full regulation comparison table across California.

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Methodology: Build cost ranges are sourced from city planning departments, licensed contractor estimates, and publicly available ADU project data for each city. Costs reflect typical new construction or conversion projects and do not account for unusual site conditions or custom specifications. Permit fee data comes from official city fee schedules. All costs are in 2025–2026 dollars. Updated quarterly.