ADU Cost & Rental ROI Calculator
Comprehensive Accessory Dwelling Unit (ADU) cost and investment calculator. Estimates ground-up detached, garage conversion, and basement in-law suite construction budgets, architectural permits, utility trenching, mortgage financing, and expected capitalization rates.
ADU Cost & Rental ROI Calculator
Estimate accessory dwelling unit (granny flat / in-law suite) construction costs, permits, utility hookups, and projected rental yields.
$211,420
$352 / sq ft all-in$1,069
P&I @ 6.5%+$731
Rent minus debt service7.66%
Estimated yield on costADU Building & Investment FAQ
What is the cheapest type of ADU to build?
Garage conversions and basement conversions are substantially cheaper ($110-$180/sq ft) than detached ground-up construction ($200-$375/sq ft) because the foundation, structural framing, and roof are already in place.
What are common hidden costs when building an ADU?
Utility upgrades (electrical panel upgrades to 200A, separate water meters, or sewer tie-ins), local impact fees, tree removal, and site grading often add $10,000–$25,000 to project budgets.
How to Use ADU Cost & Rental ROI Calculator
Choose ADU Type & Size
Select detached, garage conversion, or basement ADU and specify total square footage.
Configure Finish & Financing
Set interior finish quality and down payment or loan interest rate.
Review Budget & Cash Flow
Inspect the itemized budget breakdown, estimated monthly mortgage, and net cash flow.
Frequently Asked Questions
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