Expense ratio

Explanation

Every mutual fund and ETF charges an annual expense ratio to cover management and operating costs. You never see a bill: the fee is taken out of the fund’s assets daily, and the returns you see are already net of it. Broad index funds often charge well under 0.10% a year; actively managed funds commonly charge 0.5% to 1% or more.

Other costs can stack on top:

• Advisory fees, often around 1% of assets a year for a traditional advisor
• Plan administration fees in some 401(k)s
• Trading costs and bid-ask spreads, usually small for large index funds
• Sales loads on some mutual funds

Fees matter because they compound just like returns, in reverse. They also matter in retirement: a 1% total fee on a portfolio supporting a 4% withdrawal rate consumes a quarter of what you could otherwise spend. Unlike future returns, fees are known in advance and within your control.

In scenarios, you can enter a blended expense ratio or total fee, and the app subtracts it from returns each year. Comparing two scenarios that differ only by fee shows its long-run cost.

Example

You invest $500,000 for 30 years, and the investments earn 7% a year before fees.

• Low-cost index fund (0.03%): net return 6.97%. Ending value: $500,000 × 1.0697^30 = $3,774,243
• Higher-cost fund (1.00%): net return 6.00%. Ending value: $500,000 × 1.06^30 = $2,871,746
• Difference: $902,497

The higher-cost fund ends about 24% lower, even though the fee difference is less than one percentage point a year.