Calculate smarter. Plan better.

Interactive decision models to test assumptions, compare scenarios, and make major financial decisions with clarity. Free, fast, private, and calculated instantly in your browser.

Financial Decision Models & Simulators

Housing

Rent vs. Buy Analyzer

Compare total wealth accumulation over your time horizon. Account for equity growth, property taxes, maintenance, rent inflation, and the opportunity cost of down payments invested in index funds.

Launch Rent vs Buy Model →

Why Use whatifmoney.ai?

Instant Real-Time Math

Every calculation updates dynamically as you adjust sliders and inputs, giving immediate clarity on complex compound scenarios.

100% Client-Side Privacy

Your financial numbers never leave your browser. No mandatory accounts, no server tracking of your net worth, debts, or income.

Scenario Comparison

Test "What If" questions side-by-side: what if interest rates drop, what if you make extra mortgage payments, or what if you retire 5 years earlier?

Frequently Asked Questions

Are the financial calculators on whatifmoney.ai free to use?
Yes. All core financial simulators—including Mortgage, Retirement / FIRE, Investment Growth, Rent vs Buy, and Debt Payoff—are completely free with no paywall.
Is my financial data stored on your servers?
No. All financial calculations run locally in your web browser. We do not store or transmit your financial inputs to external databases.
How does the Rent vs. Buy calculator determine breakeven?
The model compares the total net wealth of buying (home equity minus interest, taxes, maintenance, and buying/selling friction) versus renting and investing the difference (down payment and monthly savings in broad market index funds).