Exchange-traded funds (ETFs) that track the S&P 500 have become the default long-term investment vehicle for millions of individual investors — and for good reason. A low-cost ETF like VOO (0.03% annual expense ratio) captures virtually the entire S&P 500 return after fees. The calculator above defaults to 9.97% nominal (10% minus VOO's 0.03% expense ratio) to show the real after-fee projection.
Change the nominal rate to 9% or 8.5% to model ETFs with higher expenses — or to model the fee drag of actively managed funds that charge 0.75–1.5% annually. The difference in final wealth over 20–30 years is far larger than most investors expect.
How ETF expense ratios work and why they compound against you
An expense ratio is the annual fee an ETF or mutual fund charges as a percentage of your investment. A 1% expense ratio on $100,000 costs you $1,000 per year — but the real cost is much larger because the fee reduces your compounding base. A dollar not earned in year 1 is not just a dollar lost; it is all the compounding that dollar would have generated in years 2 through 30.
The math is stark: at 10% gross return, $10,000 over 30 years grows to $174,494. At 9% (after a 1% fee), it grows to $132,677 — a $41,817 difference. The 1% annual fee cost you 24% of your final wealth. At 0.03% (VOO), the deduction is negligible: $173,968 vs. $174,494 — essentially nothing.
Tracking error: how much do ETFs actually deviate from the index?
Tracking error measures how closely an ETF follows its benchmark. For large, liquid S&P 500 ETFs like SPY, IVV, and VOO, tracking error is typically less than 0.05% per year — the ETF performance is essentially identical to the index before fees, and the expense ratio is the main driver of underperformance vs. the benchmark.
Smaller ETFs in less liquid markets may have higher tracking error due to bid-ask spreads, partial replication strategies, and the cost of managing a large number of positions. For the S&P 500, however, tracking error is a negligible concern — focus on the expense ratio.
Choosing between ETFs: VOO vs. SPY vs. IVV
All three major S&P 500 ETFs (VOO, SPY, IVV) track the same index. The differences are in expense ratio and liquidity. SPY has the lowest expense ratio at 0.0945% and the highest trading volume, making it preferred by institutional traders who trade frequently. VOO charges 0.03% and IVV charges 0.03% — both are effectively tied for long-term buy-and-hold investors.
For long-term investors, the choice between VOO and IVV is essentially a coin flip; both charge 0.03%. SPY costs about 3× more in fees (0.0945%) — over 30 years, that extra 0.0645% compounds into several thousand dollars of lost wealth on a $50,000 position. SPY's liquidity advantage is irrelevant for someone who holds for decades.
Frequently asked questions
What is the average return of a S&P 500 ETF?
S&P 500 ETFs like VOO, SPY, and IVV aim to match the S&P 500 total return minus their expense ratio. The long-run S&P 500 total return is approximately 10% per year nominal. After VOO's 0.03% fee, that is 9.97% — functionally identical to the index. After SPY's 0.0945%, it is 9.91%. Over 30 years, those tiny fractions matter, but both remain far superior to actively managed funds averaging 1–2% in fees.
How do ETF expense ratios affect long-term returns?
A 1% annual expense ratio reduces final wealth by roughly 20–25% over 30 years compared to a 0% cost equivalent. At 10% gross return, $10,000 over 30 years: 0% fee → $174,494; 0.03% fee → $173,968; 1% fee → $132,677. The fee effect is multiplicative and compounds — every dollar not earned in fees is a dollar that cannot compound for the remaining years.
Are ETFs safer than individual stocks?
ETFs are more diversified than individual stocks by design. An S&P 500 ETF holds 500 large companies, so no single company failure destroys the investment. Individual stocks can go to zero; the S&P 500 index essentially cannot (though it can decline 50%+ in a crash). ETFs are not "safe" in the sense of no price risk — they fluctuate with markets — but they eliminate company-specific risk.
Should I invest a lump sum or contribute monthly to an ETF?
Lump-sum investing statistically outperforms dollar-cost averaging (DCA) about 2/3 of the time, because markets trend upward and a lump sum is invested longer. However, DCA has lower regret risk — if markets immediately drop, you feel less of the loss. For most people, investing the lump sum as soon as available is mathematically optimal; DCA is psychologically preferable. Switch to Mode B above to model regular monthly contributions.
Worked examples
Each result is computed by the same engine that powers the calculator. Return assumptions are historical averages or user-supplied planning figures — not predictions.
S&P 500 ETF (low-cost), 5 years
$18,000 in a 0.03% expense-ratio S&P 500 ETF, total-return ending balance $29,800 after 5 years.
- Starting value
- $18,000
- Ending value
- $29,800
- Holding period
- 5 yrs
- Total ROI
- 65.6%
A 65.6% total return over 5 years is 10.64% CAGR — near the S&P 500's long-run average and achievable largely because a 0.03% expense ratio costs almost nothing ($5/year on $18k). The same 5-year period in a 1% expense-ratio fund at identical gross performance would have ended near $27,700 — about $2,100 less.
Sector ETF vs broad index comparison
$12,000 in a technology sector ETF, 3-year total-return ending balance $22,500.
- Starting value
- $12,000
- Ending value
- $22,500
- Holding period
- 3 yrs
- Total ROI
- 87.5%
An 87.5% total gain over 3 years is 23.3% CAGR — far above the broad market during a tech-heavy bull run. Sector ETFs concentrate risk: the same period would have shown dramatically different results if tech had underperformed. Measuring your actual CAGR and comparing it to the broad index reveals whether sector concentration added value on a risk-adjusted basis.
More questions answered
How do I calculate the return on an ETF?
Use your actual account balance (total-return including reinvested distributions) as the ending value. Enter your original purchase amount as the starting value and years held. The calculator returns total ROI% and annualized CAGR. If you made additional purchases over time, enter monthly contributions to get the money-weighted return (IRR) instead.
How does the expense ratio affect ETF returns?
The expense ratio is deducted from the fund's NAV continuously — it does not appear as a visible charge, but it reduces returns. A 1% expense ratio costs roughly 17% of your ending value over 20 years at 10% gross returns. On $50,000, that is about $45,000 in foregone wealth. This is why choosing a low-cost ETF (0.03–0.20% expense ratio) over a high-cost fund with similar holdings matters enormously over long holding periods.
What is the difference between an ETF return and its benchmark return?
The gap between an ETF's return and its benchmark is called tracking error. For broad-market index ETFs, tracking error is typically tiny — often 0.01–0.05% per year — because the ETF holds the same securities as the index. For some niche or leveraged ETFs, tracking error can be substantial. Always compare your ETF's stated return to its specific benchmark (not the S&P 500 unless that is the ETF's index).