This calculator estimates how an investment portfolio might grow over time using your chosen starting amount, regular contributions, one-off top-ups, an assumed rate of return and any fees you enter. It shows projected values to help compare different scenarios, but it cannot predict real outcomes. Investment values can fall as well as rise and you could get back less than you invest. Returns, charges and timing all affect the result, so use the figures as an educational guide to how compounding works rather than as a forecast.
What this calculator assumes
- The calculator uses simplified growth assumptions and cannot forecast actual market performance.
- Any fees entered are applied as part of the illustration and may not match every real-world charging structure.
- The projection does not account for tax, inflation or changes to contribution timing unless the tool explicitly includes them.
- Investment values can go down as well as up and capital is at risk.
How to read the estimate
The output shows a projected portfolio value based on the inputs you provide. The starting value is the amount invested at the beginning, while monthly contributions and one-off top-ups add extra money over time. The assumed annual return is a simplified rate used to illustrate growth, not a promise or expectation. If you include fees, the calculator can show how charges may reduce the final figure. Because markets move, actual results will differ, sometimes materially, and capital is at risk throughout the investment period.
Why assumptions matter
Small changes to return assumptions, contribution levels or fees can have a large effect over longer periods because growth can compound. A higher assumed return increases the projected end value, while fees and lower returns reduce it. This makes the calculator useful for comparing scenarios, such as steady monthly investing versus a larger initial lump sum. The estimate is most helpful when read as a range of possibilities rather than a single answer, since real-world performance depends on market conditions, fund choice and the length of time invested.
Useful official sources
FAQs
Does the calculator show guaranteed investment returns?
No. It shows an illustration based on the figures entered, including the assumed return and any fees. Real returns can be higher or lower and capital is at risk.
Why do monthly contributions make such a difference?
Regular contributions add more money to the portfolio over time, so future growth can compound on a larger base. The effect becomes more noticeable over longer periods.