Compound Interest Calculator
Project the growth of a starting amount plus monthly contributions at a fixed annual return, compounded monthly. Works in any currency.
Assumes monthly compounding and contributions at the end of each month. Returns are never guaranteed. Not financial advice.
How it works
The future value combines two parts: your starting amount growing at the compound rate, and each monthly contribution growing for however many months remain after it's deposited. The results split the total into money you put in versus interest the money earned — watching that second number overtake the first is the whole argument for starting early.
FAQ
How is compound interest different from simple interest?
Simple interest is earned only on your original amount; compound interest is also earned on previously earned interest. Over decades the difference is enormous — that reinvestment loop is the engine of long-term investing.
What compounding frequency does this use?
Monthly, with contributions added at the end of each month — the closest match to how most people actually invest (a monthly transfer into a fund).
What annual return should I assume?
That's your call, not ours. For context, broad stock-market index funds have historically averaged around 7–10% per year before inflation over long periods — with brutal short-term swings along the way.