How it works
This compound interest calculator shows how your money grows when the returns are reinvested. Enter what you have invested today, what you add each month, the yearly return you expect and how many years you will keep going. The chart splits the result in two: the money that came out of your pocket and the growth that the money itself produced.
Compound interest means that each year you earn returns not only on what you put in, but also on the returns of previous years. At first the effect is small. After ten or fifteen years it usually becomes the biggest part of the total, which is why time matters more than almost anything else.
An example
Two friends invest $500 a month at 7% a year. One does it for 10 years and ends with about $87,000. The other keeps going for 20 years and reaches about $260,000. Double the time, but three times the money: the second decade adds far more than the first because the growth is now working on a much bigger pile.
Frequently asked questions
What return should I use?
Broad global stock indexes have returned roughly 7% to 9% a year over long periods, before inflation. The tool uses 7% as a central, prudent example. It is an assumption, not a promise: real years go up and down.
Does it account for inflation and fees?
Yes, in “More options”. You can show every figure in today’s money (2% inflation a year) and add the yearly fee of your funds, so you see how much a 1% fee costs you over decades.
What does “Your money is multiplied by” mean?
It divides the final amount by what you put in. It is useful, but a small starting amount can make any multiplier look huge, so always look at the dollars too.
Is my data stored anywhere?
No. Your numbers stay in your own browser. If you create an optional account, a copy is kept only so you can open it on another device.
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