See what your investments could be worth — in today’s money, after fees
Compound growth is the effect of your investment returns earning returns of their own. Left alone for long enough, it does more of the work than your contributions do — but two things quietly work against it: the fees you pay every year, and inflation eating what each pound is worth.
This calculator accounts for both. Set your age, what you have invested and what you add each month, and it projects a range rather than a single misleading number.
Compound growth is what happens when the returns your investments earn start earning returns of their own. In year one a £10,000 pot growing at 5% earns £500. In year two you earn 5% on £10,500, not £10,000 — so you make £525 without adding a penny.
Early on the difference looks trivial. Over decades it stops being trivial: on the chart above, the gap between the dashed “paid in” line and the scenario lines is entirely money you did not contribute. For most long-term investors that gap eventually becomes larger than everything they put in themselves.
Markets do not return a tidy 5% every year. They return 22% one year, −14% the next, and 3% the year after. Any calculator that gives you a single confident figure is hiding that, and the precision is fake.
The order of those returns matters too. Two investors with identical average returns can end up with very different pots depending on when the bad years land — a risk that grows as your pot gets larger. Treat the range as the honest answer and the middle line as a reasonable planning assumption, not a forecast.
A platform charging 0.45% a year alongside a fund charging 0.22% sounds negligible. It is not, because you do not just lose the fee — you lose everything that money would have earned for the rest of your investing life.
That is why the figure above is calculated by running the whole projection twice, once with your fees and once without, and taking the difference. It is a substantially bigger number than simply adding up the charges, and it is the honest one.
£500,000 in 2060 will not buy what £500,000 buys now. Inflation steadily erodes what each pound is worth, so a large future number can be badly misleading.
Switching the toggle to today’s money re-expresses every figure in what it would be worth if you had it in your hand right now. It is usually a sobering adjustment, and it is the number worth planning against.
If you hold investments outside an ISA, our ISA transfer calculator works out what it would cost to move them in. New to all this? Start with our guide to investing for the first time in the UK.
Your balance grows each month at a rate derived geometrically from the annual growth rate, so twelve months compound to exactly the stated yearly figure. Fees are then deducted monthly as one twelfth of the annual charge, and your monthly contribution is added at the end of the month. Repeating that for every month between your current age and your target age produces the projection.
Nobody knows what future returns will be, which is why this calculator shows a range rather than one number. It uses 3% a year as a conservative case, 5% as a balanced case and 10% as an optimistic case, all before inflation. You can enter your own rate instead if you prefer a different assumption.
Far more than the headline percentage suggests. A 0.45% platform fee plus a 0.22% fund charge does not simply remove 0.67% a year — you also lose all the growth that money would have earned for the rest of your investing life. This calculator measures that by running the projection twice, once with your fees and once without, and reporting the difference.
Because inflation erodes what each pound buys. A projected pot of £500,000 in thirty years will not buy what £500,000 buys today. Switching to today's money restates the forecast in current purchasing power, which is usually the more useful number for planning.
No tax is applied, on the assumption you are investing inside a Stocks and Shares ISA where growth and dividends are sheltered permanently. If you hold investments outside an ISA, capital gains tax and dividend tax may apply to your returns.
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