How Much Does Your
ADU Really Cost?
Get an instant, location-adjusted estimate for your Accessory Dwelling Unit. Our calculator uses real construction data and regional pricing.
Free cost estimates
Updated Q1 2026
Trusted by 50,000+ homeowners
Why Use Our ADU Calculator?
Built with real construction data to give you the most accurate ADU cost estimates available.
Region-Adjusted Pricing
Costs adjusted for your state with real labor rates and permit fees, not one-size-fits-all national averages.
Updated Quarterly
Our cost data is refreshed each quarter with the latest construction prices, material costs, and permit fees.
Comprehensive Breakdown
See itemized costs for permits, design, foundation, and construction. Covers all 5 ADU types.
Frequently Asked Questions
How accurate are these cost estimates?
Our estimates are based on real construction data and updated quarterly. They should be within ±15% of actual costs for most projects, but final costs depend on specific site conditions and contractor selection.
Are permit fees included in the estimate?
Yes, our estimates include typical permit fees and design costs, scaled by your region. However, some cities have unique requirements that may add additional costs.
What's not included in these estimates?
Site-specific costs like utility connections, significant grading, or structural upgrades to existing buildings are not included. These can add $5,000–$25,000+ depending on your property.
Which ADU types does the calculator support?
We support all five common ADU types: Detached ADU, Attached ADU, Garage Conversion, Junior ADU (JADU), and Basement Conversion. Each has different base costs and construction requirements.
Can I save or share my estimate?
Yes! Use the "Get Free Contractor Quotes" button to save your estimate and receive it via email along with qualified contractor contacts in your area.