ADU CALCULATOR
Should You Build an ADU?
See how much you should spend — based on your home's value — to make an ADU a smart investment, not a money pit.
Your Property
We'll pull local rent data from HUD Fair Market Rents.
Check Zillow, Redfin, or your tax assessment.
Choose the ADU configuration you're planning.
Living area of your main home (find on Zillow listing or tax records).
Your home: $417/sq ft
Typical range: 200–1,200 sq ft.
Enter your ZIP above to auto-fill with HUD data.
Not sure what to budget? Check ADU construction costs or browse 500+ plans with estimates.
$250,000
Based on $417/sq ft × 600 sq ft
$200,000
Includes a 20% cushion against overruns.
+$0
Only $0 cushion (0% of budget) — construction overruns often hit 20%+
$21,120
After 20% vacancy & expenses on $2,200/mo.
Where Does Your Budget Fall?
What Happens at Different Spend Levels
| Cost | Value Added | Net Gain | Break-Even | Verdict |
|---|---|---|---|---|
| $100,000 | $250,000 | +$150,000 | 4.7 years | SMART |
| $150,000 | $250,000 | +$100,000 | 7.1 years | SMART |
| $200,000 | $250,000 | +$50,000 | 9.5 years | TIGHT |
| $240,000 | $250,000 | +$10,000 | 11.4 years | RISKY |
| $300,000 | $250,000 | −$50,000 | 14.2 years | RISKY |
How Financing Affects Your Break-Even
If you finance $200,000, here's how different interest rates and loan terms impact your monthly payment and time to recoup through rent.
Lower Rate
Mid Rate
Higher Rate
Watch your costs
At $200,000, you're under the Do-Not-Exceed limit of $200,000 — but only by $0 (0% of your budget). Construction projects routinely run 20%+ over budget due to permits, site conditions, and change orders. A single surprise could push you past the limit.
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Estimates only. Actual costs, rent, and value added vary by region, contractor, permits, and market conditions. Consult a contractor and financial advisor before committing.