BackyardADU

California ADU cost calculator

All-in design-build estimates in seconds. 2026 pricing, regionally adjusted. Pick your region, ADU type and size — we'll show the typical range. No email required.

Typical all-in cost
$285,000
$225,000 – $375,000
Per square foot$300 – $500
Region multiplier1.00×
Finish adjustment1.00×
What's included
  • Architecture & engineering
  • Permits & impact fees
  • Construction labor & materials
  • Standard finishes (per finish-level above)
  • Standard utility connections
What can push you 20-40% higher
  • Sloped lots requiring engineered foundations
  • Difficult site access (no driveway for materials)
  • Long utility runs from main house to ADU
  • Tree-protection or hillside review processes
  • Custom architectural features beyond catalog options

This is an estimate. Get at least three real quotes from licensed CA B-class general contractors before signing.

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Based on 2026 published pricing from Maxable, GreatBuildz, Abodu, Angi, BFPM and individual CA design-build firms. Updated quarterly. Cost figures are illustrative — not bids or warranties. See our about page for methodology.