Use this compound interest calculator to see how your savings could grow with regular investing. Enter a starting amount, a monthly contribution, an expected return and your ETF’s annual cost, and the calculator shows what your portfolio could be worth over time.
Assumes a constant annual return net of the fund cost, monthly contributions at the end of each month and no taxes. Real returns vary year to year and are not guaranteed.
How to use this compound interest calculator
- Starting amount: what you invest on day one (can be zero).
- Monthly contribution: what you add every month, for example through an ETF savings plan.
- Expected annual return: long-term global stock returns have historically averaged roughly 6-8% a year before inflation. Use a lower figure for a more cautious estimate or to think in today’s money.
- Annual fund cost (TER): the yearly cost of your ETF. Most global UCITS ETFs cost between 0.07% and 0.25%.
- Years: how long you plan to stay invested.
What is compound interest?
Compound growth means your returns start earning returns of their own. In the first years, most of your portfolio is money you put in. Over decades, investment growth can overtake your contributions, which is why starting early matters more than starting big.
Three lessons from the numbers
- Time is the strongest lever. Investing €200 a month for 30 years instead of 20 adds 50% more contributions but, at a 6% return, roughly doubles the final value.
- Small fees add up. Try changing the TER from 0.2% to 1.5%, a typical actively managed fund fee: over 30 years the difference can be tens of thousands.
- Consistency beats timing. A fixed monthly plan that keeps running through crashes buys more shares when prices are low.
Next steps
Ready to start? Read how to start investing in Europe with €100 a month and compare the best all-world ETFs to choose your first fund.
Sources
This calculator is for illustration only and is not financial advice. Investment returns are not guaranteed and you may get back less than you invest.