Rent minus mortgage is not cash flow. Know the real number before you tour.
House hacking means buying a 2 to 4 unit property (or a home with a rentable room or unit), living in one part and renting the rest. Whether it works depends on the numbers for that property. With higher mortgage rates, the other units' rent covers less of the payment than many older examples assume, so "the tenant pays my mortgage" is often not true once every cost is counted.
Before you tour, work out two numbers:
The calculator below does both. It is for checking the math, not financial advice.
Negative housing cost is what you pay each month to live there. Assumes a 30-year fixed-rate loan. Excludes closing costs, utilities you pay as the owner, and principal paydown. Estimates for educational purposes, not financial advice.
Have an address in mind? Run it in PropAnalyzer AI for net cash flow with taxes, HOA and financing included, rent comps on a map, and a 0–100 AI score in under 10 seconds. Set your down payment and rate, and watch the numbers update live.
This is an example, not a real listing or a market average. It is a duplex bought for $400,000 with 3.5% down ($14,000) on a 30-year loan at 6.75%. You live in one unit and rent the other for $1,800 a month. These are the calculator's default inputs.
This is the number most house-hack pitches stop at. It leaves out most of the cost of owning the property.
You pay about $1,659 a month to live there, not $704. Compare that with what you pay to rent today, and remember it excludes utilities you pay as the owner and the closing costs to buy.
Even with both units rented at $1,800, this example property doesn't cash flow. That is worth knowing before you buy, because one day you may move out. Change any input above to see what it takes to turn the move-out test positive: a lower price, higher rent, a larger down payment or a lower rate.
Both numbers swing on the rent you assume for the other unit. A rent guess that is $200 too high moves the result by $200 a month. PropAnalyzer AI shows nearby rent comps on a map around the property, with the median rent and range, so you can check the rent before you trust the cash flow. For a standard rental analysis, use the free rental cash flow calculator.
Screen small multifamily listings before you spend a Saturday touring them.
Enter a ZIP code, filter by Multifamily, and get the top 3 AI-ranked properties for sale with price, score and cap rate.
Open a result and see nearby rental comps on a map, with the median rent and range behind the estimate.
Change the down payment, interest rate, HOA or taxes and watch net cash flow and the AI score update live.
It depends on the numbers for the specific property, and higher mortgage rates mean the other units' rent covers less of the payment than it used to. Work out two numbers before you tour: your net monthly housing cost while you live there, with taxes, insurance, mortgage insurance, HOA and reserves included, and the property's cash flow if you moved out and rented every unit. Compare the first with what you pay to rent today. This is a way to check the math, not financial advice.
Because the mortgage payment is only part of the cost. Property taxes, insurance, mortgage insurance, HOA dues, and reserves for vacancy and maintenance all come out of the same rent. In the example on this page, rent minus mortgage is -$704 a month, but the true net housing cost is -$1,659 a month.
As of October 2026, lender guides say FHA loans allow as little as 3.5% down on an owner-occupied 1 to 4 unit property for borrowers with a credit score of 580 or higher, with mortgage insurance added to the payment. Triplexes and fourplexes must also pass FHA's self-sufficiency test. Conventional loans have their own minimums. Confirm current terms with a lender. (Source: MortgageResearch.com)
Free to download on iPhone & Android. Search a ZIP code or an address and get the real numbers in under 10 seconds.