A percentage with thirty birthdays
Set a 1% fee next to a 6% or 7% expected return and it reads as a minor deduction. That is the comparison the fee is quoted to invite, and it is wrong in a way that is not small: the charge is not taken once. It is taken every year, on the whole balance, including on the growth that previous years' fees already reduced. Over a working life it does not remove one per cent of your money; on a typical set of numbers it removes something closer to a fifth of it.
The calculator makes the deduction visible rather than inferred. It runs the same portfolio twice, once at your gross return and once at your return minus the fee, and shows the gap: the headline is the money the fee costs you over the period, with the percentage of your would-be portfolio it represents underneath, and below that sit the two portfolio figures with and without the charge.
Try the default numbers, then move the fee slider from 1% to 0.2%. The difference is usually larger than anything a person could achieve by saving harder for a year, and it requires no sacrifice at all: only a decision made once, on a platform comparison page.
Counting every layer of the charge
The common mistake is to count the fund charge and forget the platform on top, or vice versa, so add everything together. The platform or account fee, paid to the provider holding your investments, often runs 0.15% to 0.45% and is sometimes capped. The fund's own charge, the OCF, is commonly 0.05% to 0.25% for a global index tracker and frequently 0.75% to 1.0% for an actively managed fund, and neither figure includes the transaction and FX costs inside the fund, which are real but do not appear in the headline OCF. An adviser, if you use one, typically adds 0.5% to 1.0% more, and frequent dealing adds trading commissions on top of all of it.
Stack the layers and the range is startling. A total of 0.25% is achievable with a cheap platform and an index tracker; a total of 2% is entirely normal for an actively managed portfolio held through an adviser. So a 1% all-in charge is indeed common, particularly through advisers and active funds, while also being well above what a self-directed investor in index funds would typically pay. Common and cheap are not the same thing. Prising your true all-in figure out of a provider's own documents is the awkward part of this, and the fee guide shows where the numbers tend to hide. The gap between those two portfolios, over thirty years, is enormous, and this page will show you exactly how enormous on your own numbers; when you move from numbers to actual providers, the FCA's guidance for consumers is a sensible companion.
The shadow every pound casts
Money compounds. So does the absence of money.
A pound taken in fees in year one is not just a pound. It is a pound that never earned a return in years two through thirty; at 6% over thirty years, that single pound would have become about £5.74. Every year's fee casts the same shadow, and the shadows stack, which is why the loss is so disproportionate to the headline percentage. The mechanism is exactly the one that makes the compound interest calculator so encouraging when it runs in your favour. The mathematics does not care about direction.
It also means fees matter far more to someone with thirty years ahead of them than to someone with five. The younger you are, the more a fee decision is worth, which is the opposite of how most people's attention is allocated.
One convention to hold onto while reading the output: use a real (after-inflation) return and every figure is in today's money, which is how the whole site works; the inflation calculator shows what that distinction is worth. The model simplifies in other ways too. It applies fees smoothly and returns evenly, where real charges are levied monthly or quarterly on varying balances, some platforms cap their fee above a certain portfolio size, and returns arrive unevenly. For a long-run comparison of two fee levels this is close enough, but treat the output as a scale, not a statement of account. And no market delivers the same constant figure every year (nearly a century of annual returns data makes that plain); to see how the same portfolio behaves under real historical sequences, that is what the retirement backtest is for.
Two years of work, priced in
There is a second way to read the number, and it is the one that tends to change behaviour. If the fee costs you a sum equal to two years of contributions, then paying it means working roughly two years longer for the same outcome. To see that directly, take the fee cost from this page and try lowering your expected return by the same fee percentage in the FIRE calculator. The retirement date moves. The sensitivity tool shows which inputs your plan is most exposed to, and for long horizons costs are usually near the top.
None of which makes a fee automatically bad. It is a price, and the question is what you get for it: an adviser who stops you selling everything in a crash may earn their charge several times over in a single decision, and a fund with a higher OCF that gives you access to something you genuinely need is not waste. Lowest cost is a strong default for a straightforward portfolio, not an absolute rule. What this page does is put a number on the price, so the value can be judged against it.
Two boundaries remain. Tax is not modelled: fees inside a pension or ISA behave differently from fees in a taxable account, where charges may be deductible in some jurisdictions and the drag interacts with tax on gains. And switching has its own costs, since exit fees, out-of-market time during a transfer, and crystallising a gain in a taxable account can all offset a lower ongoing charge for the first few years. Check before moving. This is an educational calculation, not advice about which provider or fund to use; what is right depends on circumstances this page knows nothing about.