San Diego ADU cost calculator (2026 permit data)
How does this calculator work?
Pick your ADU type and we show what similar 2026 City of San Diego permits declared: the middle half and the median, plus a panel upgrade if you need one. A garage conversion declared a median of $81,800; a new 1-story detached ADU $125,900. These are lower-bound construction values, not quotes.
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Ranges, not quotes. Where a number comes from City permit values it is a lower-bound estimate: permit values are declared construction values and many use a standard rate.
Where every number comes from
- Construction values: City of San Diego development permits (data.sandiego.gov), building permits issued Jan 1–Oct 15, 2026 that add exactly one ADU (JADU row: permits adding only a JADU), declared valuation > $0. Middle half = 25th–75th percentile.
- Why a floor: of the 23 single-ADU permits that list a floor area, 8 work out to exactly $165.67 per sq ft, a sign that many values come from a standard valuation rate, not a contractor bid. Design, engineering, fees and finishes not declared are extra.
- Panel upgrade ranges: Bright Pro Electric, San Diego (updated Sep 2026).
- Impact fees: City of San Diego Information Bulletin 400 (Jan 2026) and SDMC §142.0640.
Questions
How much does an ADU cost in San Diego in 2026?
2026 City of San Diego permits that add one ADU declared a median of $120,900 of construction. Garage conversions declared a median of $81,800 and new 1-story detached ADUs $125,900. Declared values are a floor; design, engineering, fees and undeclared finishes are extra.
Are these numbers quotes?
No. They are construction values applicants declared on City permits, and many appear to use a standard valuation rate. Use them as a lower bound and compare 2–3 written quotes.
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