Cost guide
ADU cost in Los Angeles.
An ADU in the LA area typically costs $100,000 to $450,000 or more, and the biggest factor by far is which of these two projects you’re actually doing — converting an existing garage, or building new.
Three rough tiers
Uses the existing structure, so the cost goes mostly into interiors, plumbing, electrical, and insulation rather than new construction. The cheapest path to a legal ADU.
Ground-up construction, typically 600–900 sq ft. Most 2026 Los Angeles estimates land around $350–$500 per square foot all-in, including design and permits.
Larger units (1,000+ sq ft), premium finishes, or difficult sites — hillside lots, Westside neighborhoods, extensive utility work — push well past the typical range.
What actually moves the price
- Converting vs. building new. An existing garage already has a foundation, framing, and a roof — building a detached unit from scratch means paying for all of that from zero.
- Site conditions. A flat lot with easy utility access costs far less than a sloped lot needing retaining walls, extended utility runs, or drainage work.
- Permits and soft costs. Design, engineering, and permitting in LA typically run $15,000–$45,000 combined, on top of construction — easy to forget when comparing a bare per-square-foot number.
- Whether you’re adding a kitchen. A full kitchen (required for a legal ADU, optional for a junior ADU or simple conversion) adds plumbing, electrical, and ventilation work that a studio or bedroom conversion doesn’t need.
- Size. Smaller units cost more per square foot, since fixed costs (a kitchen, a bathroom, utility hookups) get spread across less space.
Why the range matters more than one number
ADU cost estimates online vary more than almost any other project type — partly because “ADU” covers everything from a converted garage to a custom two-bedroom house. The only way to know your real number is a contractor who’s seen your actual lot and garage or yard.
Ranges synthesized from multiple 2026 Los Angeles-area ADU builders and cost guides; actual sources vary significantly and several have a commercial interest in the numbers they publish, so treat this as a planning range, not a quote. Get itemized bids from licensed local contractors for a real number.
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