See how a starting balance and a regular monthly contribution grow over time — and exactly how much of the final total is your own money versus interest earned. Compounding is what turns steady saving into real wealth. Nothing is sent to a server.
Compounding is the engine; a plan tells you when it gets you to financial independence. The complete FIRE Calculator adds inflation, taxes in 43 countries, pensions, Monte Carlo stress-testing and your whole life plan — free and private.
Open the full FIRE planner →Compound interest is interest earned on your interest. Each period, the growth is added to your balance, so next period you earn returns on a bigger pile — and the one after that, bigger still. Over a few years the effect is modest; over decades it's enormous, which is why starting early beats saving more later. Albert Einstein reportedly called it the eighth wonder of the world.
For a starting amount that grows plus regular deposits, the future value is two pieces — the lump sum compounding, and an annuity of your contributions:
Final = P·(1+i)N + C·[ ((1+i)N − 1) ÷ i ]
where P is your starting amount, C each contribution, i the rate per compounding period, and N the number of periods. The coloured bar above splits your final balance into what you put in (starting amount + contributions) versus the interest compounding earned you — the gap is the whole point of investing early.
This calculator uses a fixed rate in nominal terms. Real returns vary year to year, and inflation erodes future money — the full FIRE Calculator handles both.
Related: Savings rate calculator · Coast FIRE · How long will my money last?
Estimates only, not financial advice. Assumes a constant rate and steady contributions in nominal terms; real returns vary and inflation reduces future buying power. Your inputs stay in your browser — nothing is sent to a server. · Full planner · All calculators · Savings rate · Coast FIRE · How it works · Español · Português · Deutsch · Français · Italiano · Nederlands · Svenska · Norsk · Dansk · Polski · Čeština · Suomi · Ελληνικά · Türkçe · Bahasa Indonesia · Bahasa Melayu · 日本語 · 한국어 · 中文 · ไทย · עברית · العربية · Feedback