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House Hack Cash Flow Calculator
House hacking — living in one unit, renting others — can turn your housing cost into cash flow. Whether a duplex, triplex, or single-family with ADU, this calculator sizes effective housing cost and return on the minimal down payment required for owner-occupied financing.
Your effective housing cost
$2,649
Total rental income
$1,400
Total monthly property cost
$3,937
Monthly P&I
$2,852
Annual cash flow (positive = profit)
-$31,790
Cash-on-cash ROI
-100.1%
Total cash invested
$31,750
How the math works
$475K duplex, 5% down FHA: $23,750 down + $8K closing = $31,750 in. Mortgage $2,850 + tax $475 + ins $140 + maint $200 + MIP $270 = $3,935/mo. Rental unit at $1,400 × 92% = $1,288. Effective housing cost: $2,647/mo. Cheaper than renting a comparable unit at $2,400-$3,000.
If rent fully covers the payment, effective cost goes negative (positive cash flow). A 3-unit triplex with two rentals at $1,200-$1,500 each often hits net cash flow positive. Best wealth-building move for early-career professionals who qualify for owner-occupied financing.
How to Use
- Enter purchase price, owner-occupied down payment %, and mortgage details.
- Enter monthly rental income from each non-owner unit.
- Add operating cost including your unit's maintenance share.
- See effective housing cost (what YOU pay per month), net cash flow, and cash-on-cash ROI.
Frequently Asked Questions
Can I use FHA for a house hack?
Yes. FHA allows 2-4 unit owner-occupied with 3.5% down. 5+ unit requires commercial financing. You must live in one unit for at least 12 months to maintain FHA eligibility.
What about conventional owner-occupied?
Fannie/Freddie allow 2-4 unit owner-occupied with 5-15% down. Slightly higher down than FHA but no MIP (FHA has permanent MIP at low down payment). Strong credit (700+) makes conventional cheaper long-term.
Does rental income count for qualification?
Yes but with a haircut. Lenders count 75% of projected rental income from non-owner units for DTI. Requires signed leases or market rent appraisal. Subject property income counts after 2-3 years of tax returns; at purchase, it's based on appraisal.
Is it worth it?
Usually yes for 2-4 unit deals where rental income covers 60-100% of mortgage + operating. Your effective housing cost drops to $200-$800/mo vs $1,800-$2,500 in rent. Build equity in the same time period. Real wealth-builder for 20s-30s.
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