How to read a house-hack budget
House hacking puts you in one unit and paying tenants in the rest. Their rent, after its own costs, goes toward your housing bill. The number to read first is what you still owe each month: a smaller bill, not free housing.
Keep your housing benefit apart from rent collected
The tool pulls vacancy, maintenance, reserves, and any utilities you cover out of the other units' rent, then sets what's left against your modeled housing payments. A surplus means rent covers those payments. Repairs you didn't enter, taxes on the rental income, and the landlord work are yours.
The savings line measures against what you'd pay to rent a place like your unit. The percentage divides a year of that housing savings by the cash you brought to closing, so it counts the roof over your head. That isn't cash-on-cash on a rental you don't live in.
Read the financing screens as rough drafts
For down payments under 20%, the tool adds mortgage insurance at 0.7% of the loan per year. That's an illustration, not a PMI or FHA MIP quote, and what you pay upfront and monthly depends on the loan you're offered. Take the figures off your lender's Loan Estimate and put the quoted terms in here.
On three- and four-unit properties, the 75% rent screen shown here is shorthand. FHA's self-sufficiency test uses appraiser-estimated rent from all units, less the greater of the appraiser's vacancy and maintenance estimate or 25%. Your lender runs the current version and makes the call, so treat a pass here as a reason to go ask, not an approval. HUD Handbook 4000.1
Run the household budget, not just the property
Empty a unit. Add a repair. Raise the insurance quote. Then read the leases, your city's rental rules, and the owner-occupancy term you're agreeing to, and think through sharing a wall with your tenant. Keep cash for your own life alongside the building's. To see the same property as a straight rental, run it through the rental property calculator.
Get the other units covering most of that payment and you're saving money every month you live there.