Compound interest: how small monthly amounts grow
Investing a little every month feels slow at first. The magic is that, given time, your growth starts to earn growth of its own.
👉 Change the numbers above — it’s your money, your assumptions.
Your money makes money - then that makes money
Start with €1,000, add €150 a month, and assume a steady 6% a year. In the tool above, watch how the orange ‘growth’ part of each bar is tiny in the first years and then quietly overtakes the money you actually paid in. That crossover — where your returns start out-earning your own contributions — is compounding doing the heavy lifting.
A worked example, in real numbers
Put numbers on it. Paying in €150 a month for 30 years means you personally contribute about €54,000. At a steady 6% assumed return, the projection lands far above that — the difference is growth stacked on earlier growth, year after year. Compounding is just gains earning gains: this year’s growth joins the pot, so next year’s growth is calculated on a slightly bigger number, and the gap widens every year. The Performance that includes reinvested dividends — the fuller picture of what you actually earned. More → counts both price changes and reinvested income, which is what makes the snowball roll.
Time matters more than the amount
Drop the number of years from 30 to 15 and watch the projected value fall by far more than half. Then put it back and instead halve the monthly amount — the result barely moves by comparison. The lesson: how long you stay invested is usually a bigger lever than how much you add each month, which is why starting earlier tends to matter more than adding more later.
Teaches: time beats amount — starting earlier and then stopping still beats investing three times as much money, just later
Illustrative example: €150/month, 6%/yr assumed return (this guide's own figures) — not a forecast.
Honest caveat: returns are not a straight line
Real markets do not deliver a smooth 6% every year — some years are strongly positive, some are sharply negative, and your money can be worth less than you put in, especially over short periods. The calculator assumes a steady return to show the shape of compounding, not to predict your outcome. An The fund automatically reinvests dividends back into itself, so your holding grows without cash payouts. More → fund reinvests dividends for you automatically, which keeps this snowball rolling with no action from you.