About RatesAndAmort

Our mission

Most loan and credit card tools stop at a monthly payment. That number is useful, but it hides what matters most: how long the debt will last and how much of your money goes to interest. RatesAndAmort exists to put those numbers in front of you, clearly, before you make a decision.

We hold ourselves to three commitments:

• Show the full picture. Every calculator reports total interest, a payoff date and a complete schedule, not just a payment.
• Show our work. Every formula is published on the page that uses it, with a worked example you can check by hand.
• Respect your privacy. Calculations run in your browser. The balances, rates and payments you type are never sent to us.

How the calculators work

Every calculator runs on a single, dependency-free calculation engine written in TypeScript. The same code produces the numbers you see in the calculator, the worked examples in our articles and the figures in our tests, so the site cannot contradict itself.

• Installment loans and mortgages use the standard fixed-rate amortization formula, M = P × r ÷ (1 − (1 + r)⁻ⁿ), with the monthly rate equal to the annual rate ÷ 12.
• Credit cards are simulated month by month: interest on the opening balance, then the payment. Minimum payments are the greater of a percentage of the balance or a dollar floor, recalculated monthly.
• Debt snowball and avalanche simulations pay every minimum, then send the remaining budget to the target debt and roll any surplus to the next one in the same month.
• Rounding happens at the cent, every month. The final payment absorbs any residue so schedules end at exactly $0.00.
• Testing: the engine is covered by an automated test suite that checks known results, such as standard mortgage payments, zero-interest loans, unpayable balances and calendar edge cases, before every release.

Each calculator page lists its assumptions and limits. In general, we do not model fees, variable or promotional rates, new charges, or daily interest accrual, because those depend on your specific agreement. Results are estimates for comparing choices, not payoff quotes.

Methodology last reviewed October 22, 2026.

Editorial standards

• Primary sources first. Rates, balances and rules come from sources such as the Federal Reserve, the Federal Reserve Bank of New York, the Consumer Financial Protection Bureau, Freddie Mac, the IRS and Federal Student Aid. Each article lists its sources.
• Numbers you can reproduce. Worked examples state every input so you can enter them into the calculator and get the same answer.
• Dated and reviewed. Articles show a published or updated date. Time-sensitive posts are reviewed when the underlying data or law changes.
• Balanced on policy. When we cover proposals such as interest rate caps, we present the main arguments on each side and do not take a political position.
• No paid placement. We do not accept payment to feature, rank or recommend any lender or product. If the site displays advertising, ads are clearly labeled and kept separate from calculator results.
• Corrections. If you find an error, email [email protected]. We review every report and correct confirmed errors promptly, noting material corrections on the page.

Who runs the site

What we are not

RatesAndAmort is an educational publisher. We are not a lender, broker, credit counselor, tax preparer or financial adviser, and nothing on this site is a recommendation to take any specific financial action. For decisions about your situation, consider speaking with a qualified professional, such as a certified financial planner, a HUD-approved housing counselor or a nonprofit credit counseling agency.

Get in touch

Questions, corrections or ideas for a new calculator are welcome. Use the contact page or email [email protected].