Finance Calculators

Two engines drive almost everything in this category, and they run in opposite directions. Amortisation is the borrowing engine: a loan is repaid in equal payments, but each payment splits between interest — charged that month on the outstanding balance — and principal, so early payments are mostly interest and late payments are mostly principal. Compounding is the saving engine: interest is added to the balance and itself starts earning interest, so growth accelerates the longer money is left alone. Every tool here is one of those two engines, an inversion of one (the savings-goal solver runs compounding backwards), or a comparison between the paths they produce — fixed payment against minimum payment, avalanche against snowball, margin against markup.

This category follows three house rules, and they are stated on the tools themselves rather than buried in small print. First, rates are always yours to enter: there are no built-in property-tax schedules, sales-tax or VAT tables and no stored inflation series, because those figures differ by country, city and product, change by law, and quietly rot — a stale table producing a confident wrong answer is worse than asking you for the one number only you can know. Second, the projection tools are arithmetic, not advice: they compound the balance, contributions and rate you supply and show the result, without recommending amounts, ages, products or rates. Third, every figure can be checked: formulas are printed in plain notation, worked examples show their substitutions, and schedules and year tables expose the intermediate rows, so any number on any page can be reproduced with a hand calculator.

Finally, the privacy rule that applies across Kwikfig applies with extra force to money: every calculator in this category runs entirely in your browser. Balances, debts, salaries and savings targets are never uploaded, stored or tracked — close the tab and they are gone. Use the tools in whatever order your question demands: size a payment on the Loan Calculator, interrogate its schedule in the Amortization Calculator, test a payoff strategy against your cards, then check what the same money becomes in the Compound or Future Value tools. The numbers will not always be comfortable — minimum-payment interest totals rarely are — but they will always be yours, shown with their working.