Expense Ratio Calculator

An expense ratio is the annual fee a fund charges, expressed as a percentage of assets. A 1% expense ratio on a $100,000 portfolio costs $1,000 per year — but that is the least alarming way to think about it.

The real damage is compounding. Fees do not just reduce this year’s return; they reduce the base on which all future returns compound. A dollar of fees paid in year one costs you not $1 but every future dollar that dollar would have generated.

Value without fees: V x (1 + r)^n Value with fees: V x (1 + r - expense)^n

The gap between these two lines grows exponentially over time, not linearly.

Vanguard’s S&P 500 index fund runs 0.03% per year. Many actively managed mutual funds charge 0.75% to 1.25%. On a $100,000 investment growing at 8% over 30 years:

• At 0.03%: ~$970,000
• At 1.00%: ~$761,000
• Difference: ~$209,000

That $209,000 is what the extra 0.97% in fees cost over 30 years — more than twice the original investment. The fund company kept it; you did not.

This is why the shift from active funds to index ETFs over the last two decades represents one of the largest wealth transfers from Wall Street to ordinary investors in history. The math is straightforward. The behavior change was harder.

One nuance: expense ratios do not appear on your statement as a line item. They are deducted from the fund’s net asset value daily, invisibly. You never see a bill — which is exactly why most investors underestimate their impact.