Compound Interest Calculator

How much is your money really growing? Most compound interest calculators hand you a gross figure. Once tax is withheld and inflation is taken into account, what you actually keep is a different number. This app shows all three side by side: GROSS, NET and REAL. SIX CALCULATORS, ONE APP • Compound interest — How your savings grow over time, with a starting amount, regular contributions, an annual escalation and your choice of compounding interval. Year-by-year breakdown and a growth chart. • Solve for a goal — Works backwards from the amount you want: the rate, the time, the regular contribution or the starting capital needed to reach it. • Loan & instalments — Monthly payment, total repaid and the true cost of borrowing. The amortisation schedule shows how much of each instalment is principal and how much is interest, and it works out what settling early would cost and save. • Deposit & term accounts — Term counted in days, and the amount you receive after withholding tax. Rates that change with the length of the term are applied by band. • Retirement & FIRE — Your FIRE number from your own safe withdrawal rate, how far along you are and how many years are left. Coast FIRE included, all in today's money. • Inflation & purchasing power — What today's money will be worth later, what past money is worth now, and the real return left once inflation is stripped out of a nominal one. TAX AND INFLATION ARE ACTUALLY CALCULATED Tax rules are not hard-coded. They are dated rule packs: Turkey, Germany, Brazil, Spain, and a generic pack where you enter your own rate. Withholding that changes with the length of a deposit is applied by band, and an annual allowance is respected where the country has one. Inflation is handled with the Fisher equation rather than a rough subtraction — over a long horizon the difference is not small. ACCURACY Money and rates are computed in decimal arithmetic, never in floating point, and rounding happens only when a figure is printed, never between steps. Results are checked against fixed test vectors produced by an independent reference calculator. SAVE, COMPARE, SHARE Save your calculations, then put two scenarios side by side and read the difference as a percentage — the app marks which input actually differs. Share a result as PDF or CSV, and keep your latest saved figure on a home screen widget. WORKS OFFLINE, NO ACCOUNT NEEDED Every calculation runs on your device and returns the same answer in airplane mode. There is no sign-up and no account. Your inputs and saved calculations never leave your phone; the internet is used only to verify a subscription. FIVE LANGUAGES, LOCAL FORMATS English, Turkish, German, Spanish and Portuguese (Brazil). Currency and number formatting follow your region. There is a separate wording mode for participation banking, where profit share replaces interest. Light and dark themes, phone and tablet layouts. PRO SUBSCRIPTION All six calculators are free and stay free; the free version keeps three saved calculations. Pro unlocks unlimited saves, scenario comparison, PDF and CSV export, the home screen widget and the extra colour themes. Weekly, monthly and yearly plans are available, and the monthly and yearly plans start with a free trial. Price, period, renewal and how to cancel are shown on the purchase screen before you buy. The subscription renews automatically at the end of each period until cancelled; you can cancel any time in your Google Play account settings. IMPORTANT This app is a calculator. Its results are for information only and are not investment, tax or legal advice. Tax rates and legislation change; check current rules and a qualified professional before any significant decision. Future returns cannot be guaranteed.