California ADU Cost Calculator & Permit Guide
Your ADU budgetstarts here
Choose your city, ADU type, and size to see permit fees, construction cost, local permit steps, and review-time information before you hire a designer or contractor.
No account · Sources and review dates shown
- California cities researched
- 100+
California cities researched
Permit-fee data organized city by city.
- Free to use
- $0
Free to use
No account or payment required.
- Planning answers in one report
- 3
Planning answers in one report
Permit fees, City process, and a construction-cost range.
Three questions, one report
- 1.
Which city?
Search all 100 cities we cover. The ten most-requested are one tap away.
- 2.
What are you building?
Detached, attached, a garage conversion, or a junior ADU inside the house. The type sets the size range and which local rules we pull in.
- 3.
Roughly how big?
Slide to your target floor area and watch permit fees and construction cost move together as you cross the sizes we hold data for — including the 750 sq ft line.
750 sq ft detached ADU in Los Angeles
GetYourPermit research estimate, low to high
$5,300 – $13,700
- Requested size
- 750 sq ft
- Fee model reference
- 800 sq ft
- Typical permit budget
- $9,000
Typical build cost at LA averages, hard cost only
$281,500
Valuation basis $300,000 · City-specific research references available
Researched permit-fee ranges for an 800 sq ft detached ADU
All 100 cities| City | Research range | |
|---|---|---|
| Los Angeles | Los Angeles County | $5,300 – $13,700 |
| San Jose | Santa Clara County | $9,803 – $17,055 |
| San Francisco | San Francisco County | $9,741 – $15,104 |
| Oakland | Alameda County | $12,074 – $22,217 |
| Sacramento | Sacramento County | $5,150 – $16,000 |
| Fremont | Alameda County | $10,303 – $19,183 |
| Berkeley | Alameda County | $16,183 – $23,184 |
| Sunnyvale | Santa Clara County | $12,595 – $22,210 |
| Mountain View | Santa Clara County | $15,878 – $23,687 |
| San Mateo | San Mateo County | $8,832 – $16,432 |
ADU permit process, city by city
Fees are half the question. Each guide covers who reviews your plans, where you apply, what to prepare, and how long review usually takes — summarized from the city’s own pages.
- Los AngelesDepartment of Building and Safety · ePlanLA
- San JoseDevelopment Services Permit Center / Building · SJePlans
- San FranciscoDepartment of Building Inspection · DBI inspection scheduling and payment
- OaklandBuilding Bureau · City of Oakland Online Permit Center
- SacramentoBuilding Division · Sacramento Public Permit Portal
- FremontBuilding and Safety Division · Citizen Access
- BerkeleyBuilding and Safety Division · Permits Online
- SunnyvaleBuilding Division · E-OneStop Permit Center / Public Portal
- Mountain ViewBuilding Division · Mountain View ePermitsMV / Online Permit Portal
- San MateoBuilding Division · Customer Self-Service (CSS) Portal
What California law sets, and what your city decides
- Review is ministerial
- For complete ADU applications covered by State law, local agencies generally have 60 days to approve or deny without a public hearing. Your city still sets the fees, forms, and filing portal.
- 750 sq ft is the fee line
- ADUs of 750 sq ft or less are exempt from local development impact fees. Above 750 sq ft, cities may charge impact fees in proportion to the primary home. School and utility fees follow their own rules.
- Size and height floors
- State law protects a path for qualifying ADUs up to 800 sq ft with at least 16 ft of height and 4 ft side and rear setbacks. Local allowances may be more generous, and parcel-specific safety rules still apply.
- Junior ADUs are different
- A JADU is a unit up to 500 sq ft inside the existing home. It usually needs an owner-occupancy agreement and skips most impact fees.
- Pre-approved plans save time
- Some cities publish or accept pre-approved ADU plan sets. They may reduce repeat review of the building design, but the city must still review the parcel, site plan, utilities, and local conditions.
Statewide summary sources: the California Government Code and the California HCD ADU Handbook. Confirm the current city rule for your parcel before filing.
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Common questions
Researched for planning, without false precision
Most cities do not publish one all-in ADU fee schedule. We combine published fee references with project-planning research to produce a practical low, typical, and high range for each city, ADU type, and reference size.
Nothing here is a quote. Fees change with your parcel, your plans, and the day your permit is issued. Read the methodology.