Mutual Fund Calculator
See what a mutual fund investment grows to — and what the expense ratio quietly takes. Enter your starting amount, monthly additions, expected return, fee, and holding period to compare your ending balance with and without fees.
Contributions, growth & fee cost
How your fee compares
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Compare platformsHow fund fees eat returns
A mutual fund’s expense ratio is skimmed from the fund’s assets every day before the share price is published, so you never see a bill. The damage compounds twice: you lose the fee itself, and you lose everything that money would have earned for the rest of the holding period. Over one year the difference between 0.75% and 0.05% looks trivial; over twenty years of contributions it can swallow a five-figure chunk of your final balance.
This is why fee comparisons matter more than most fund-picking decisions: the fee is one of the few things about a fund’s future you know with certainty.
How it’s calculated
We simulate month by month: the balance grows at the gross monthly rate (annual return ÷ 12), the fund deducts the monthly fee (expense ratio ÷ 12 × balance), then your contribution is added. The no-fee run repeats the simulation with the fee set to zero. Fees charged = the sum of monthly deductions; total fee drag = no-fee ending balance − after-fee ending balance, which includes the compounding those fee dollars would have produced.
Assumes a constant return and constant contributions; real markets vary year to year. Sales loads, taxes, and trading costs are not modeled. Estimates only — not investment advice.
Worked example
Invest $10,000 up front plus $500 a month for 20 years at a 7% gross return. In a fund charging 0.75% you end with $272,624. With no fee the same money grows to $300,851. The fund collected $17,227 in fees, but your total cost is $28,227 once you count the growth those fees never earned — about 9.4% of your final wealth, on contributions of $130,000. In a 0.05% index fund you would end with roughly $298,864 — about $26,240 more than the 0.75% fund.
Common mistakes
- Judging a fee by its size in year one instead of its compounded cost over the full holding period.
- Entering a fund’s published (net) return as the gross return — published returns already have the expense ratio removed.
- Ignoring sales loads and 12b-1 fees, which come on top of the expense ratio in some share classes.
- Paying an active-fund fee for a closet index fund that hugs its benchmark.
Where it is used
- Comparing an employer 401(k) menu — the cheapest adequate fund usually wins.
- Deciding whether to move an old high-fee fund into an index fund.
- Quantifying what “only 1%” actually costs over a career of contributions.
- Checking an adviser-sold fund against a self-directed alternative.
Frequently asked questions
Is a 0.75% expense ratio high?
It is above average. The asset-weighted average expense ratio for U.S. equity mutual funds was about 0.42% in 2023, and index equity mutual funds averaged about 0.05% (ICI 2024 Investment Company Fact Book). Plenty of broad index funds now charge 0.10% or less, so 0.75% only earns its keep if the manager reliably beats the market by more than the difference.
Why is the total cost bigger than the fees I actually paid?
Every dollar taken as a fee also stops compounding for you from that day on. In the worked example the fund collects $17,227 in fees over 20 years, but the ending balance is $28,227 lower than the no-fee case — the extra $11,000 is growth those fee dollars would have earned.
Does the expense ratio show up on my statement?
No — that is what makes it easy to ignore. The fund deducts it from assets daily before calculating the share price, so you never see a line item. Your return is simply lower than the fund's gross return by roughly the expense ratio each year.
What about sales loads and transaction fees?
Some funds add a front-end load (charged when you buy), a deferred load (charged when you sell), or 12b-1 marketing fees. This calculator models the ongoing expense ratio only, which is usually the biggest long-run cost. If your fund charges a 5% front-end load, only 95 cents of each dollar is invested from day one — a hurdle most no-load funds never impose.
Is the return I enter before or after fees?
Enter the gross annual return you expect the fund's holdings to earn. The calculator subtracts the expense ratio for you. Note that published fund returns are already net of the expense ratio, so a fund reporting 7% net with a 0.75% fee earned roughly 7.75% gross.