Free finance calculators with transparent assumptions

FinTools is a set of free, browser-based calculators for compound interest, investing, retirement, 401(k) contributions, debt payoff, loan payments, APY, and savings goals. Every calculator shows its formula, assumptions, and limitations next to the result.

Calculators

Compound Interest Calculator Estimate how balances may grow from principal, contributions, rate, and time. Investment Calculator Project investment balances with contributions, return assumptions, inflation, and fee drag. Retirement Calculator Project whether savings may last through a planning age using transparent retirement assumptions. 401(k) Calculator Project 401(k) balances with salary contributions, employer match, 2026 limits, inflation, and fees. Debt Payoff Calculator Compare debt payoff timelines from balances, APRs, minimums, and extra payments. APY Calculator Convert APY and nominal annual rates with compounding frequency comparisons. Savings Goal Calculator Find the monthly deposit needed to reach a savings target by your chosen month. Loan Calculator Estimate monthly principal and interest payments and view your loan amortization schedule.

Educational only

FinTools pages are for general planning education, not financial, investment, tax, legal, or retirement advice.

Assumption-led

Calculators make inputs and assumptions visible instead of implying certainty about rates, returns, inflation, taxes, or personal outcomes.

Browser-first

Calculators run in your browser without live rates or financial account connections. Save named calculations locally only when you choose; no account or device sync.