Compound interest means that returns are added to the balance and can generate their own returns later. Over short periods the effect can look small, but over decades the reinvested gains often become the largest part of the final portfolio.

The calculator combines future value for the starting amount with the future value of recurring contributions. It adjusts the calculation for the selected compounding frequency and contribution frequency, so weekly deposits with monthly or daily compounding can be modelled separately.

Yes. Enter the starting portfolio, monthly ETF savings rate, assumed annual return and investment horizon. The result shows final value, your own deposits, the estimated growth portion and a year-by-year schedule.

The annual savings amount, return and time horizon usually matter more than the exact rhythm. Still, contribution timing can create small differences, and weekly saving may fit some income patterns better than one monthly transfer.

The calculator does not recommend a return. A practical approach is to test several scenarios, such as conservative, base and optimistic assumptions, and then check whether the plan still works if returns are lower than hoped.

No. This calculator shows nominal investment growth before taxes, product costs, trading fees and inflation. For retirement spending, use the withdrawal simulator afterwards because taxes and inflation matter more once money is being taken out.

Time gives early returns more years to compound. That is why the last years of a long plan often add more wealth than the first years, even when the contribution stays the same.

First estimate the pension or income gap you want to cover. Then use the compound interest calculator to test whether the savings rate can build enough capital. Finally, use the withdrawal simulator to turn the projected portfolio into monthly retirement income.