Setting up the building
The property type opens on duplex. Switch it to triplex or fourplex if that's what you're buying. For each unit you won't live in, enter the rent you expect. If you don't know it, check what similar units nearby rent for. The appraiser will set a market rent figure later, and that's the number the lender uses.
Fill in your income, debts, credit score and cash the same way you would on the main calculator. Pick the county carefully. Loan limits climb with unit count, and taxes and insurance on a multi-unit building run higher than on a house, so adjust those fields if you have quotes.
The rules the calculator applies
Rent counts as income
Lenders take 75% of the other units' rent and add it to your gross monthly income. Then they run the normal ratios. On FHA that's 46.9% for housing and 56.9% total. On Conventional it's 50% total. The 25% they leave out covers vacancy and repairs.
The self-sufficiency test on 3 and 4 units
FHA adds a second test on triplexes and fourplexes. Take the market rent of every unit, your own included, and multiply by 75%. That figure has to equal or beat the full monthly payment. A building can pass your personal ratios and still fail this test, so the calculator checks both.
Reserves and limits
FHA wants three months of the full payment in the bank after closing on 3 and 4 unit homes. QualRate models Conventional and VA at six months on any 2 to 4 unit home. USDA doesn't finance 2 to 4 unit homes, so it drops out of the results here.
Loan limits rise with each unit. In lower-cost counties the 2026 FHA limit is $693,050 for a duplex, $837,700 for a triplex and $1,041,125 for a fourplex. The loan limits page shows the figure for your county.
A duplex in Broward
A buyer earns $4,200 a month and has $300 in monthly debts. On a single-family home in Broward, FHA at 5.75% tops out around $242,200.
Now the buyer looks at a duplex and expects the other unit to rent for $1,700. Lenders count 75%, which is $1,275, so qualifying income becomes $5,475.
| Item | Amount |
|---|---|
| Qualifying income | $5,475.00 |
| Max housing payment (46.9%) | $2,567.78 |
| Max after debts (56.9% less $300) | $2,815.28 |
| FHA duplex price | about $328,100 |
| 3.5% down payment | $11,482.95 |
The housing ratio sets the limit. The tenant's rent raises the buyer's price by about $85,900.
A triplex that falls short
Take a $600,000 triplex where each unit rents for $1,800. Total rent is $5,400, and 75% of that is $4,050. The full FHA payment at 3.5% down is $4,461.39, which is more than $4,050. It fails self-sufficiency regardless of the buyer's income. At these rents, the triplex price that passes is about $540,900. Three months of reserves at $600,000 would be $13,384.17.
Before you make an offer
If the rent pushes you into range, run the property through the price check and the cash to close calculator. If income is still short with the rent counted, a parent or grandparent can co-sign. On 2 to 4 units FHA limits a non-occupant co-signer loan to 75% of the value, so compare that against Conventional's 5% down in the co-signer calculator. The house hacking guide covers the rental documents lenders ask for.
Once you've found a building you like, call AAA Capital Funding at 888-601-8344 and we'll check the rents, the self-sufficiency test and your reserves with you.