Expense Ratio Calculator: What Fees Really Cost
Two funds. Same return. Different fee. Drag the sliders and watch the gap open up over the decades — this is the most expensive small number in personal finance.
That’s of your ending balance, handed over in fees — on total contributions of .
Navy line = lower-fee fund. Red line = higher-fee fund. The space between them is money that left your pocket.
This is neutral compound-interest arithmetic, not a forecast. It assumes both funds earn the same gross return and differ only by their expense ratio, deducted monthly — which isolates the one variable you actually control. Real funds differ in return too, and nobody can predict that part, which is exactly why we focus on the part that’s knowable. The default 7% is illustrative, not a promise; markets do not deliver smooth returns.
Why one number matters this much
The fee is small and certain; the harm is large and delayed, which is precisely why it’s underrated. A 0.70% fund doesn’t feel 17 times more expensive than a 0.04% fund — both look like rounding errors on a statement. But fees compound on the same schedule your money does, quietly skimming a slice of every year’s growth, including the growth the fee already prevented in prior years. Run the sliders to a realistic career-length horizon and the gap routinely reaches into the six figures.
This is also the rare investing variable with no trade-off. A cheaper index fund isn’t riskier or worse-diversified than its expensive twin — it’s the same market exposure for less. See the lowest-cost options in each category on our best index funds page.