ADU / In-Law Suite Cost Calculator
Estimate the cost to build an ADU or in-law suite based on type, size, and your location.
Last updated: March 25, 2026
ADU / In-Law Suite Cost Calculator
Estimate the cost to build an ADU or in-law suite based on type, size, and your location.
Estimated Total
$170,000
Itemized Breakdown
This calculator provides estimates based on national averages adjusted for your region. Actual costs may vary significantly based on specific project conditions, contractor availability, material prices, and local market factors. Always get at least 3 quotes from licensed, insured contractors before starting your project.
Want the full picture?
Read our complete ADU / In-Law Suite Construction cost guide with material comparisons, contractor tips, savings strategies, and regional pricing data.
Quick Cost Reference
Cost by Tier
Garage conversion ADU (400 sq ft) - kitchen, bathroom, bedroom, electrical upgrade, no exterior changes. Most affordable ADU type.
Detached backyard ADU (600 sq ft) - new construction on concrete foundation, full kitchen, bathroom, bedroom, separate utilities, standard finishes
Custom detached ADU (800+ sq ft) with high-end finishes, vaulted ceilings, full kitchen, 1.5 bathrooms, separate utilities and address, premium landscaping