Test the Real Math Before You Make Your Next Financial Move.
Stop guessing. Whether you're buying a house, drowning in high-interest debt, facing inflation pay cuts, or starting an e-commerce side hustle—audit the unvarnished mathematical reality in seconds.
Rent vs. Buy Reality Audit
Uncover hidden property taxes, maintenance CapEx, and S&P 500 opportunity cost.
Directly compare 10-year wealth trajectories between buying a home vs renting and investing down payment capital into diversified equity index funds.
Launch Rent vs Buy Audit →Debt Destroyer & Payoff Accelerator
Calculate exact debt-free dates and compare Avalanche vs Snowball.
Break the minimum monthly payment trap. Audit how adding $50 to $300 in monthly accelerator payments truncates years off your payoff timeline and saves thousands in bank interest fees.
Launch Debt Destroyer →Salary & Purchasing Power Inflation Audit
Audit true inflation-adjusted living wages across 2001–2050.
Did you get a raise or a pay cut? Calculate your real purchasing power erosion against cumulative Consumer Price Index inflation and determine the exact salary needed to preserve your living standard.
Audit Purchasing Power →Side-Hustle Profit Margin Audit
Calculate true net profit after marketplace fees, ad spend, and 15.3% tax.
Strip away top-line vanity metrics. Audit true take-home earnings per order and calculate your effective hourly wage after accounting for platform take-rates, shipping, and self-employment taxes.
Audit Profit Margins →Frequently Asked Questions
Is Finance Tester really 100% private and client-side?
Yes. All financial calculations, salaries, debt balances, and profit margins are computed exclusively inside your browser using client-side JavaScript. No numbers are ever sent to our servers or saved to a database.
Why are standard mortgage calculators misleading?
Most calculators only display Principal and Interest, hiding 1%–2% annual maintenance reserves, HOA fees, property tax hikes, and the massive opportunity cost of tying up your down payment in illiquid real estate.
How does the Debt Destroyer calculate payoff schedules?
Our engine uses dynamic monthly compound amortization models, applying extra payments directly to principal balances to save you maximum interest.