Skip to main content

Index Fund Growth calculator

Project an index-fund position factoring in expense ratio drag.

Loading calculator…

About this calculator

Index funds track a market benchmark (S&P 500, Total US Market, MSCI World) and charge a small annual expense ratio (ER) for the privilege. This calculator projects an index-fund position over time, factoring in the ER drag — which seems tiny per year but compounds into meaningful sums over a multi-decade horizon.

How expense ratios eat returns

A 1% ER doesn't sound bad until you compound it. Over 30 years at a 10% gross return, a 1% ER reduces the effective return to 9% — and the difference between $100,000 growing at 10% vs 9% for 30 years is $446k. Vanguard's pioneering research (and Jack Bogle's career) was largely about making this drag explicit.

Current ER landscape (2024)

  • VTI / SCHB / ITOT (total US market) — 0.03–0.04%
  • VOO / SPY / IVV (S&P 500) — 0.03–0.10%
  • VT (total world) — 0.07%
  • Average actively-managed fund — 0.5–1.0%
  • Legacy retirement plan funds — sometimes 0.5–1.5%

When an expensive fund makes sense

Almost never for passive exposure. If you want US large-cap, the 0.03% ER index is mathematically identical to the 0.50% ER actively-managed S&P 500 fund — minus the fee. For factor exposure (small-cap value, momentum, etc.), some active management may add value net-of-fees, but the bar is high. SPIVA reports consistently show 80%+ of active funds underperform their benchmark over 10 years.

Frequently asked questions

What’s the difference between an ETF and a mutual fund?
ETFs trade intraday like stocks, often have tax advantages (less capital gains distribution), and typically have lower ERs. Mutual funds settle at end-of-day NAV. For most investors, the index ETF is the right choice. Inside a 401(k), the choice is often limited to mutual funds.
Are index funds really better than active funds?
After fees, on average, yes — by a wide margin. The SPIVA Scorecard shows 87% of US large-cap active funds underperformed the S&P 500 over the trailing 15 years. There are exceptional active managers, but identifying them in advance is extraordinarily difficult.
What about a total market vs S&P 500?
Total market includes small and mid caps (~3,500 stocks) vs S&P 500’s 500 large caps. Historically the two have nearly identical returns because large caps dominate the index. Either is fine. Total market gives slightly more diversification for the same ER.
Should I add international index funds?
Standard advice: 20–40% of equities in international diversifies but adds currency risk. The data on whether this helps vs hurts is genuinely mixed. A 100% US equity allocation has done fine historically but has higher concentration risk than a global portfolio.
Index fund growth: $25k + $6000/yr at 10% for 30 years | SuperCalculator