House Hacking Calculator
Calculate your effective housing cost when renting out spare rooms.
House Hacking Calculator — Live for Free by Renting Rooms
House hacking is the millennial wealth-building secret: buy a home, rent out spare rooms or units, and let tenants pay your mortgage. This calculator shows your effective monthly housing cost when you rent out 1–4 rooms — often dropping it to $0 or even negative (you get paid to live there).
How to use this tool
- 1
Enter your mortgage and housing costs
Principal + interest + tax + insurance + utilities.
- 2
Set rent per room
Check Zillow/Craigslist for comparable room rentals in your area.
- 3
Pick number of rooms rented
Most people rent 1–3 spare rooms or units.
- 4
See your effective housing cost
Plus 5-year wealth boost.
Pro tips
- FHA loans allow 3.5% down on duplexes/triplexes/4-plexes — perfect for house hacking.
- Charge market rate — friendship discounts hurt you long-term and the tenant.
- Always have a written lease — even with a friend. Protects both sides.
Frequently asked questions
Is house hacking legal?
Yes — renting spare rooms in your primary residence is fully legal in most cities. Check local short-term rental laws separately.
Do I pay tax on the rent?
Yes — rental income is taxable, but you can deduct a proportional share of mortgage interest, tax, depreciation, and utilities.
What about Airbnb instead?
Higher revenue but more work and many cities now restrict it. Long-term roommates are more passive.
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