Eddie Kendall

House Hacking Calculator

Mortgage minus rent is the easy version. It’s also incomplete. Add taxes, insurance, vacancy, repairs and management to see what the property may actually cost you. Example numbers are loaded. Replace them with your own.

Purchase & financingYou can model $0 down, but zero-down financing is not available to every buyer or loan.
Property costsEnter annual taxes and insurance, plus monthly recurring costs.
Rental assumptionsStarting percentages are editable examples, not recommendations.
Management

Estimated personal housing cost / month

…

After modeled rental friction, not just gross rent.

Mortgage principal & interest…
Total fixed property cost…
Effective rental contribution…
Fixed costs offset by rent…

The easy math vs. the modeled estimate

The easy math

… Mortgage P&I minus gross rent

The more realistic estimate

… All modeled costs minus effective rent

Difference…

That first number is the version that makes house hacking look almost stupidly simple. The second is closer to what owning the place may actually cost.

See the calculation
Loan amount… Mortgage principal & interest… Property taxes / month… Insurance / month… Vacancy allowance… Maintenance reserve… Management…

Why I built this

When I bought my duplex, the easy math was mortgage minus rent. Actually owning it taught me that vacancy, repairs, management and other costs matter too. This calculator lets you plug in your own numbers and see the difference.

Read what my duplex actually cost me

How the estimate works

The calculator first estimates monthly mortgage principal and interest with the standard fixed-rate amortization formula. It adds monthly taxes, insurance, HOA and owner-paid recurring costs. Then it reduces gross rent by your vacancy allowance, maintenance reserve and, if selected, management fee.

Editable starting assumptions

The 5% vacancy reserve, 5% maintenance reserve and 8% management fee are placeholders so the calculator has something to model. They are not universal rules. My published duplex example uses an 8% management fee; your costs may be different.

What this calculator leaves out

  • PMI or MIP, closing costs and loan-specific fees
  • Tax deductions, depreciation and income taxes
  • Appreciation, rent growth, refinancing and resale costs
  • Lender qualification, credit, DTI and financing eligibility
  • Future rent from the unit you live in

Use this as an estimate, not a verdict

This calculator does not tell you whether to buy a property. Results depend entirely on the assumptions you enter and are not financial, tax, legal or lending advice. Your inputs are calculated in your browser and are not saved or sent anywhere.