House Hacking Calculator — Your Effective Housing Cost

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House hacking calculator

Living in one unit or room and renting out the rest? Enter your total monthly ownership cost and the rent from each rented space to see what you effectively pay to live there.

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The short answer

Last updated: July 2026

House hacking means living in part of a property you own while renting out the rest. Effective housing cost = total monthly ownership cost − rent collected. If your mortgage, taxes, insurance, and utilities total $2,600 and your tenants pay $2,400, you effectively pay $200 a month to live there.

House hacking calculator

What do you really pay to live there?

Enter your total monthly ownership cost and the rent from each unit or room you rent out. The tool shows your effective housing cost and how much of the bill your tenants cover.

Total monthly ownership cost

Mortgage payment (PITI) plus utilities and other costs you pay as the owner.

Rented units or rooms

Add a unit or room

Input-driven result

Your inputs

Formula

Result below

Effective monthly housing cost

$200

$2,600 ownership cost − $2,400 rent collected.

Rent collected

$2,400

Across 2 rented units/rooms.

Share of housing cost covered

92%

Rent collected ÷ total ownership cost.

Monthly housing offset

Ownership cost

$2,600

Rent collected

$2,400

Your remaining cost

$200

Estimate based on your inputs. Not a promise of results.

Estimate only. This assumes every unit is rented and paying — it doesn't model vacancy, repairs, turnover, or taxes on the rental income. Lending, zoning, and occupancy rules for owner-occupied rentals vary by place.

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How it works

How this tool works.

House hacking is the classic first move in rental real estate: buy a small multifamily or a house with spare rooms, live in one part, and let rent from the rest carry the mortgage. The appeal is simple — your biggest monthly expense shrinks, sometimes to zero, while you learn landlording with the property you live in.

This calculator shows what that looks like with your numbers. Enter everything you pay monthly as the owner — mortgage principal and interest, taxes, insurance, and the utilities you cover — then add a row for each unit or room you rent out. The tool nets the rent against the cost and shows your effective monthly housing cost and the percentage your tenants cover. It’s a snapshot of a fully rented month, built entirely from your inputs.

Enter your total monthly ownership cost: the full mortgage payment (PITI) plus utilities and other costs you pay as the owner.

Add a row for each rented unit or room with the monthly rent it brings in (or the rent you expect to charge).

The tool subtracts total rent from total cost — the result is your effective monthly housing cost, or a surplus if rent exceeds the cost.

It also shows the offset percentage: how much of your housing bill the rental income covers.

Make the result useful

Model the owner-occupied month honestly

House hacking compares total monthly ownership cost with rent from the spaces you rent. Include mortgage, taxes, insurance, utilities you pay, and any other recurring owner cost.

A fully rented month is not an annual result. Test vacancies, repairs, roommate turnover, and local rules before treating the offset as guaranteed.

Worked example

If total monthly ownership cost is $2,800 and rented rooms bring $2,100, the modeled owner cost is $700 for that month before repairs and vacancy.

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Does rent cover all ownership risk?

No. It is only one month’s modeled income against costs.

Answers

Questions, answered plainly.

What does “effective housing cost” mean?

It’s what living there actually costs you each month after rental income: total ownership cost minus rent collected. If the number is negative, the rent more than covers the bill on the month you modeled — you live there at no monthly cost with cash left over.

What does this tool not tell me?

It models one fully rented, fully paying month. It doesn’t account for vacancy between tenants, repairs and maintenance, turnover costs, CapEx, or income tax on the rent — all of which raise your true cost over time. Treat the result as a best-case monthly snapshot, not an annual average.

Are there rules about renting out part of the home I live in?

Often, yes. Zoning, occupancy limits, rental registration, and lender owner-occupancy requirements vary by state, city, and loan type — and renting rooms in your own home is treated differently in some places than renting separate units. Check your local rules and your mortgage terms before listing.

Does the rent I collect count as taxable income?

Rental income is generally taxable, and renting part of your primary residence has its own treatment for splitting expenses between personal and rental use under current IRS rules. This tool does pre-tax cash math only — confirm the tax side with your CPA.

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