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📊 Based on ARMLS September 2026 Phoenix Metro DataSend us your results and we'll review your specific lot — lot size, setbacks, HOA, and utility access — and give you an accurate build cost and ROI estimate. Free, no obligation.
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Based on ARMLS September 2026 Phoenix metro data. Updated quarterly.
For most Phoenix homeowners, yes. Based on ARMLS September 2026 data, a casita in the Phoenix metro generates $1,400 to $2,200 per month in long-term rental income and adds $120,000 to $200,000 in appraised home value. At an average build cost of $133,000 to $325,000, the cash-on-cash return typically runs 7% to 11% depending on size and neighborhood. For multigenerational use, the avoided cost of assisted living ($4,500 to $6,000/mo) makes the ROI calculation even more favorable.
ADU ROI is calculated as: (Annual rental income ÷ Total build cost) × 100. For a $163,000 casita renting at $1,600 per month, gross annual income is $19,200 and the cash-on-cash return is 11.8%. The payback period — build cost divided by annual income — is approximately 8.5 years. This understates total return because it excludes the permanent equity the casita adds to the property from day one. See our Casita Cost Guide for a full breakdown.
Based on ARMLS September 2026 data, Phoenix metro small rental units (400 to 1,000 SF) rent for a median of $2.00 per square foot per month, with a range of $1.09 to $4.20 per square foot. A 400 SF Studio casita rents for approximately $800 to $1,200 per month. A 720 SF Retreat rents for $1,400 to $2,000 per month depending on neighborhood and finish level. Scottsdale and Arcadia zip codes are at the top of the range; South Phoenix and Encanto are at the lower end.
Based on ARMLS September 2026 Phoenix metro sales data, a permitted, site-built detached ADU adds approximately $282 per square foot in appraised home value on average, with a range of $170 to $385 per square foot depending on neighborhood and finish quality. A 400 SF Studio adds approximately $113,000 in home value. A 720 SF Retreat adds approximately $203,000. The value addition is permanent and shows up in your property assessment the year after the Certificate of Occupancy is issued.
The payback period — build cost divided by annual rental income — typically runs 8 to 14 years in the Phoenix metro depending on model size, neighborhood, and rental rate. Smaller models and higher-rent neighborhoods like Arcadia and Scottsdale shorten the payback period. The payback calculation alone understates total return because it doesn't include the equity the structure adds to your property from day one.
Rental rate defaults reflect the ARMLS median rent per square foot for small residential units (400–1,000 SF) across the Phoenix metro as of September 2026, with a range of $1.09 to $4.20 per square foot. Home value defaults reflect the ARMLS median price per square foot added by permitted ADUs in recent Phoenix metro sales. Build cost defaults reflect Valley Casita Co.'s actual per-square-foot construction costs for each model, including permits, labor, materials, and a standard finish package.
The calculator uses real Phoenix metro market data to give you a realistic planning estimate. It is not a formal appraisal or a binding quote. Final build cost depends on your specific lot conditions — utility run distance, grading needs, HOA requirements, and Scottsdale vs. Phoenix permit fee differences. Final rental value depends on your neighborhood, unit finish level, and market timing. Use the calculator as a directional tool, then send us your results for a site-specific assessment at no cost.
We review your specific lot — setbacks, HOA, utility access, lot size — and give you an accurate build cost and ROI estimate in one conversation.