Investment calculator
See what a starting amount plus a monthly contribution could grow into, and how much of that growth fund fees quietly eat. Set your numbers and the chart updates instantly; the dashed line shows the money you put in, the orange area is what compounding adds on top.
A projection, not a promise: real markets do not return the same percentage every year, and this simple model ignores taxes, inflation and trading costs. Returns compound monthly at your yearly rate minus the fund fee.
From projection to portfolio
A projection only becomes a plan once you pick actual funds. The cheapest way most investors outside the US implement it is one or two broad UCITS ETFs, for example an S&P 500 fund or a whole-world fund, held for years. You can also build and backtest a full portfolio with the same data that powers this site.
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Frequently asked questions
What yearly return should I assume?
Nobody knows future returns, but long-run history gives reference points: broad stock indices like the S&P 500 have averaged roughly 7 to 10% a year before inflation over many decades, and global portfolios slightly less. Many people model with 5 to 7% to stay conservative. Try a few values and look at the range rather than a single number.
Why does a small fund fee matter so much?
The fee is subtracted from your return every single year, so it compounds against you. Over 30 years, the difference between a 0.07% index fund and a 1.5% actively managed fund can easily exceed 20% of your final pot. That is why the calculator includes a fee field.
Does the calculator include inflation or tax?
No. Results are in today's money terms only if you use an inflation-adjusted return (for example 5% instead of 8%). Taxes depend entirely on your country and account type, so check your local rules.
What is compound interest, in plain words?
It is growth on top of growth. Year one, your money earns a return; year two, that return also earns a return, and so on. Early on the effect looks small, but given a decade or two it becomes the dominant force in the chart, which is why starting early beats starting big.
Which funds do people actually use for this?
The classic building blocks are broad index UCITS ETFs, for example an S&P 500 fund like CSPX or VUAG at 0.07% a year, or a whole-world fund like VWCE at 0.22%. You can compare all of them on this site and simulate a full portfolio in the portfolio builder.