Compound interest calculator

The annual return is converted to an equivalent monthly one. Each month the balance grows by that return, then the deposit is added. Gains are reinvested, so they earn returns in turn: that is compound interest. The annual fee comes off the return every year as a percentage of the balance, and is not deducted a second time; “what it costs” includes the growth that money would have earned.

The value in today's money divides the final sum by the rise in prices over the whole period. It shows what the money could buy, not how much there will be.

The return is a constant assumption. Real investments vary from year to year, sometimes a lot. For a picture based on historical data, use the backtest.