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ADU Cost Calculator · Los Angeles

How much does an ADU cost
in Los Angeles?

Enter your ADU size and type below. We'll show you the typical Los Angeles cost range — then show you exactly how much a CALI ADU Signature Home costs at the same size. One number. Fixed. In writing.

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What drives ADU costs in Los Angeles?

Every ADU project is different, but the cost drivers are predictable. Understanding them helps you budget accurately — or avoid them entirely with fixed pricing.

Size and layout

Cost per square foot decreases as the ADU gets larger — a 400 sqft studio costs more per sqft than a 1,200 sqft three-bedroom because fixed costs (permits, engineering, utility connections) are spread over more area. Two-story designs cost more to frame but use less of your lot.

Design phase

Custom architecture adds $15,000–$40,000 and 2–4 months before permitting can even begin. Then plan check takes 4–6 months because the city hasn't reviewed those plans before. Pre-designed plans (like our Signature Homes) eliminate this cost and time — the drawings are already engineered and permit-ready, cutting plan check to 6–8 weeks.

Permits and fees

City permit fees, school fees, and plan check fees typically run $5,000–$15,000 depending on jurisdiction and ADU size. These are set by the city, not the builder. Plan check takes 4–6 months for custom designs because the city is seeing those drawings for the first time. Pre-engineered plans like ours clear in 6–8 weeks.

Site conditions

Sloped lots, poor soil, long utility runs, tree removal, and tight access all add cost. A flat, clear lot with utilities nearby is the cheapest to build on. We identify site costs during the free consultation — never after the contract.

Finish level

Builder-grade finishes run $250–$350/sqft for construction only. Mid-range (quartz counters, solid cabinetry, name-brand fixtures) runs $350–$450/sqft. High-end custom finishes push past $500/sqft. All CALI ADU Signature Homes include mid-to-high-range finishes in the fixed price.

Change orders

The #1 reason ADU projects go over budget. Industry average: 10–15% in change orders on custom builds. With 126 ADU projects in Los Angeles, we've already encountered and solved for every common site condition — which is why we can offer a fixed price and mean it.

ADU cost questions

How much does it cost to build an ADU in Los Angeles in 2026?
In 2026, a new detached ADU in Los Angeles typically costs $300–$550 per square foot all-in (design, permits, construction, and finishes). That puts a 600 sqft one-bedroom at roughly $180,000–$330,000 and a 1,200 sqft three-bedroom at $360,000–$660,000. CALI ADU Signature Homes fall at the low-to-mid end of this range with premium finishes included, because pre-designed plans eliminate custom architecture costs and our volume of projects reduces per-unit construction costs.
Is it cheaper to convert a garage or build new?
Garage conversions typically cost 30–50% less than new detached construction because the foundation and framing already exist. A typical garage conversion runs $150–$300 per square foot. However, existing garages often have structural limitations, low ceiling heights, and moisture issues that add unplanned cost. New construction costs more upfront but gives you a purpose-built home with no compromises.
What's included in the cost per square foot?
It depends on who's quoting. Many contractors quote construction cost only — which excludes design, engineering, permits, appliances, and site work. Always ask what's included. CALI ADU's fixed price covers everything from design through certificate of occupancy: architectural drawings, engineering, permit processing, construction, finishes, appliances, fixtures, and inspections.
How much do ADU permits cost in Los Angeles?
City permit fees for an ADU typically range from $5,000 to $15,000 depending on the size and your jurisdiction. This includes plan check fees, building permit fees, and school impact fees. Utility connection fees (water, power + gas) add another $3,000–$8,000. These fees are set by the city and utility companies, not the builder.
Why do ADU cost estimates vary so much?
Because most ADU builders use a cost-plus model — they estimate the work, start building, and adjust the price as surprises appear. Lot conditions, permit delays, design changes, and subcontractor pricing all introduce variability. Fixed-price contracts eliminate this entirely: you know the cost before you sign. After 126 ADU projects in Los Angeles, we've already priced in the surprises.

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