Master your debt with precision.

Six free calculators built for people who actually run the numbers. No signup. No email capture. Just the math, done right, in your browser.

Credit Card Minimum Payment

See exactly how long it takes to pay off a credit card with minimum payments — and how much interest the bank earns from you.

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Snowball vs Avalanche

Compare the two most popular debt payoff strategies side-by-side. See which one saves more money and which one keeps you motivated.

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Debt-to-Income Ratio

The exact number mortgage lenders look at before approving you. Color-coded against the federal 36% and 43% thresholds.

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Loan Payoff

Mortgages, auto loans, student loans, personal loans — see how much extra payments save you in time and interest.

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Compound Interest

Project the future value of your investments with monthly contributions. The math behind every retirement plan, made visible.

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Real Estate ROI

Cash flow, cap rate, and cash-on-cash return on rental properties. The same metrics professional landlords use.

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Why we built this.

Most financial calculators online are buried in popups, behind email walls, or wrapped in advertising for a service nobody asked for. We built DebtToolbox the way calculators should work: open the page, type your numbers, get the answer. That's it.

Every calculator on this site uses the same formulas as federal regulators (CFPB, SEC, FHFA, IRS) and major US banks. We verified each one against established calculators from Bankrate, NerdWallet, and the SEC's own Investor.gov tool. Where there are sources, we link them. Where there aren't, we explain the math.

The site is free. It will always be free. We make money from a few unobtrusive ads — never popups, never tracking beyond what the ad networks themselves do. Your numbers stay in your browser; nothing gets sent to a server.