What the number is
A fund's expense ratio is its annual running cost, expressed as a percentage of the assets it manages. A 0.20% ratio means the fund takes 0.20% of your holding each year to pay for management, administration, custody, audit and record-keeping.
Two things people routinely get wrong:
- You never see it charged. There is no line item and no deduction from your bank account. It is accrued daily inside the fund's net asset value, so it silently reduces the price of every share you hold. Your return is already net of it.
- It is charged on your whole balance, not on your gains. A 0.75% ratio costs 0.75% of the balance in a year the fund falls 20%, just as it does in a year it rises 20%.
What it costs over 30 years
$100,000 invested for 30 years, 7% gross return
| Expense ratio | Net return | Final value | Cost vs 0.03% |
|---|---|---|---|
| 0.03% (large index fund) | 6.97% | $754,849 | — |
| 0.25% | 6.75% | $709,637 | $45,211 |
| 0.75% | 6.25% | $616,408 | $138,441 |
| 1.00% | 6.00% | $574,349 | $180,500 |
The 0.75% fund is not 0.72 percentage points worse — it ends up 18% smaller. The fee itself compounds, because every dollar taken in year 3 is also a dollar that cannot grow for 27 more.
Assumptions: a single lump sum, a constant 7% gross return, the fee deducted annually, no taxes, no contributions. Real returns vary; the relative gap between the columns is the robust part.
Reframe it as a share of your return rather than of your assets. At a 7% gross return, a 1.00% fee takes about one-seventh of the return every single year, in good years and bad.
Costs an expense ratio does not include
The ratio is a floor, not the total. Also check for:
- Transaction costs incurred inside the fund when it trades. High-turnover funds pay these constantly and they sit outside the headline ratio.
- Bid–offer spread when you buy or sell an ETF — a one-off cost that matters if you trade often.
- Platform, custody or account fees charged by your broker on top of the fund's own fee.
- Entry, exit or performance fees, common in some markets and unusual in others.
- Currency conversion if the fund is priced in another currency — see how conversion fees work.
- Tax drag, which depends on your country, your account type and the fund's domicile, and can easily exceed the expense ratio.
Regulators require a standardised total-cost disclosure in many markets — the EU's KID “ongoing costs” figure, for instance — precisely because the expense ratio alone understates the total.
When a higher fee can be defensible
Not every cheap fund is better than every expensive one. A higher ratio can be reasonable when:
- The asset class is genuinely expensive to run — small-cap, emerging-market or niche fixed-income funds cost more to operate than a large-cap index fund, everywhere.
- The alternative is not investing at all, because a cheaper option is not available in your market or account.
- The fund does something you actually want that a cheap index fund does not do.
What is not defensible is paying an extra 0.7% for a fund that holds essentially the same index as a 0.05% fund. That comparison — same exposure, different price — is the one to make.
How to check yours
- Find the fund's factsheet or KID/KIID and read the ongoing-charges figure, not the marketing page.
- Add your platform fee to it. That sum is your real annual cost.
- Compare against the cheapest fund available in your market and account type with the same exposure — not against a US fund you cannot buy.
- Multiply the difference by your balance to see the annual cash cost, then check it against the 30-year table above before deciding it is small.
Sources and further reading
Primary sources are preferred: regulators, central banks, statistical agencies, tax authorities, index providers and original research. Links open on the publisher's own site; FinSage has no commercial relationship with any of them.
- U.S. SEC, Investor.gov — mutual fund fees and expenses.
- SEC Office of Investor Education — “How Fees and Expenses Affect Your Investment Portfolio” (PDF), which works the same compounding example.
- ESMA — PRIIPs Key Information Document rules, the EU standard requiring a total ongoing-costs disclosure.