Index Fund Expense Drag Calculator
Fund expense ratios reduce your net return every year. Because of compounding, even a fraction of a percent shaved from returns leads to dramatically lower wealth over decades. This calculator compares two funds with different expense ratios over your chosen time horizon, showing exactly how much the fee difference costs you in final portfolio value. The formula uses the standard compound growth calculation: FV = PV * (1 + r - e)^n, where r is the gross annual return and e is the expense ratio.
Expense drag formula
FV = PV * (1 + r - e)^n + C * [((1 + r - e)^n - 1) / (r - e)]
where: PV = initial investment, r = gross annual return, e = expense ratio,
n = years, C = annual contribution
Fee drag = FV(low-cost) - FV(high-cost)
Each fund's final value is calculated using the compound growth formula with the net return (gross return minus expense ratio). The fee drag is the difference in final values between the low-cost and higher-cost funds.
Why fund fees matter so much
- Expense ratios compound against you every year: a 1% fee on a 7% gross return means you only earn 6% net.
- Over 30 years, 1% in annual fees can consume roughly 25% of your total ending wealth relative to a 0.04% fund.
- Broad market index funds routinely charge 0.02% to 0.10%, while many actively managed funds charge 0.75% to 1.50%.
- The SEC requires funds to disclose expense ratios in their prospectus. Always check before investing.
- Transaction costs, fund turnover taxes, and load fees are separate from the expense ratio and add further drag.
Expense drag: frequently asked questions
What is an expense ratio?
An expense ratio is the annual fee charged by a mutual fund or ETF, expressed as a percentage of assets under management. A 0.10% expense ratio on a $10,000 investment costs $10 per year. This fee is deducted from the fund's returns before they are passed to investors.
How does a small difference in fees add up over time?
Due to compounding, even a 1% difference in annual fees can cost tens of thousands of dollars over a 30-year period. A $100,000 investment growing at 7% for 30 years is worth about $761,000 at 0% fees, but only about $574,000 at 1% fees. The difference is $187,000.
What is a good expense ratio for an index fund?
For broad market index funds, expense ratios below 0.10% are considered excellent. Many major index funds from Vanguard, Fidelity, and Schwab charge between 0.02% and 0.10%. Actively managed funds often charge 0.50% to 1.50% or more.
Is the expense ratio the only cost of owning a fund?
No. Other costs include trading commissions (now zero at most brokers), bid-ask spreads for ETFs, tax inefficiency from fund turnover, and load fees (front-end or back-end) charged by some mutual funds. The expense ratio is the most visible and consistent cost.
Where can I find a fund's expense ratio?
The expense ratio is disclosed in the fund's prospectus and on the fund's fact sheet. The SEC requires all funds to disclose this figure. You can also find it on your broker's website or on the SEC's EDGAR database.
Official sources
- U.S. Securities and Exchange Commission: How Fees and Expenses Affect Your Investment Portfolio.
- SEC Mutual Fund Fee Calculator methodology: SEC Mutual Fund Cost Calculator.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.