What are the real returns of index funds?

Short answer: about 10% a year before inflation, about 7% after — measured over nearly a century of U.S. stock market history. That is the honest long-run figure for a broad index fund. Everything else is details, and the details matter more than the headline.

The "10% a year" number gets repeated so often it has become furniture. Financial blogs cite it. Advisors cite it. Your uncle cites it. It is roughly true, and it is also the kind of truth that misleads everyone who does not read the footnotes. The real return — what your money can actually buy — is lower. The path is bumpier. And the decades you happen to live through change everything.

Here is the number, with the footnotes attached.

The headline number and where it comes from

The most-quoted figure comes from the S&P 500, the index of 500 large U.S. companies that most index funds track. From 1928 through 2025, it delivered an annualized total return of roughly 10% per year, with dividends reinvested. That is nearly a century of data, through depressions, wars, inflation, crashes, and booms. It is one of the most durable statistics in all of finance.

A few things to notice about it. First, it assumes you reinvested every dividend — the ~1.5–2% annual dividend yield is a meaningful part of the total. If you spent the dividends, your return was lower. Second, it is an average, and averages in markets are liars: no single year ever returned exactly 10%. Third, and most important, it is measured in nominal dollars — dollars that ignore what those dollars can buy.

The inflation tax

Inflation is the quiet partner in every investment return, taking its cut before you ever see a statement. Over that same 1928–2025 stretch, U.S. inflation averaged around 3% a year. Subtract it, and the real return — the growth in actual purchasing power — drops to roughly 7% a year.

Seven percent is still a remarkable number. Money doubling in purchasing power roughly every ten years, with no skill required, is the closest thing to a free lunch markets offer. But the gap between 10 and 7 is the difference between a retirement projection that works and one that does not. A surprising amount of bad financial planning is just people compounding at 10% in a spreadsheet while living in a 7% world.

The gap gets worse in bad stretches. Take 2000 through 2025: the S&P 500 returned about 7.7% a year nominally, but only about 5.1% in real terms. Same market, same index — a full quarter-century that came in well below the century average. Which brings us to the uncomfortable part.

Decades matter more than averages

Here is the thing the headline number hides: returns cluster. The 2010s delivered annualized real returns above 11% — a golden decade that made buy-and-hold look effortless. The 2000s, bookended by the dot-com crash and the financial crisis, delivered a negative real return for the entire decade. Ten years of investing, and your purchasing power went backward.

This is not a flaw in the data. It is the data. Markets do not deliver 7% real like a salary; they deliver feast and famine that average out over periods longer than most people's patience. An investor who started in 2000 and checked in 2010 felt like index investing was a scam. The same investor who checked in 2020 felt like a genius. Neither feeling was about skill. Both were about timing.

The practical lesson: the "real return" of index funds depends heavily on when you start counting. Anyone selling you a single number without a time horizon is selling you a story, not a statistic.

Fees: the small number that eats the big one

Index funds are cheap, and that cheapness is a large part of why they work. A typical S&P 500 index fund charges around 0.03% a year in expenses. On a $100,000 portfolio, that is $30 a year — essentially nothing.

Compare that to the actively managed alternative. The average actively managed equity fund charges close to 1% a year. That sounds small too, until you compound it. Over 30 years, a 1% annual fee on a portfolio growing at 7% real shaves off roughly a quarter of your final wealth. Not a quarter of the gains — a quarter of everything.

This is the least dramatic and most important section of this article. Fees are the one part of returns you can control completely, and they compound with the same relentless math as the returns themselves. The difference between a 0.03% fund and a 1% fund, held for a working lifetime, is the difference between retiring comfortable and retiring worried.

Taxes take another bite

Nobody's real return is the pre-tax return, but tax treatment varies enough by country and account type that a single number would be dishonest. The honest version: in a taxable account, dividends and realized gains get taxed along the way, which can drag your effective return down by a meaningful fraction of a percent each year. In tax-advantaged retirement accounts, that drag mostly disappears.

The boring takeaway is the useful one: where you hold your index funds matters almost as much as which ones you hold. Max out the tax-advantaged accounts first. It is the highest guaranteed return available in personal finance.

Dollar-cost averaging: the beginner's edge

There is one more piece of good news hidden in the volatility. Most people do not invest a lump sum once and wait thirty years. They invest a little every month — dollar-cost averaging — and that habit quietly improves the deal.

When prices fall, your fixed monthly contribution buys more shares. When prices rise, it buys fewer. Over time, you automatically buy more when things are cheap and less when they are expensive — the exact opposite of what emotions tell you to do. During the brutal 2000s, an investor who kept contributing monthly ended the decade in far better shape than the lump-sum investor the headline numbers describe, because the cheapest shares of the decade were bought in 2008 and 2009.

Dollar-cost averaging does not beat the market. It beats the investor's own worst instincts, which, for most people, is the higher-value victory.

What "real" means for your planning

So what should you actually plan on? Financial planners who do this for a living typically use 5–7% real for long-horizon U.S. equity projections — below the century average, deliberately, because planning on the average is planning on luck. For a globally diversified portfolio, many use lower still.

A useful mental model: take the historical 7% real, subtract a margin for the possibility that your investing lifetime looks more like 2000–2025 than 1928–2025, subtract fees and taxes, and you land somewhere around 4–5% real for conservative planning. If reality delivers more, you retire early. If it delivers what you planned, you retire on time. Planning is one of the few places in life where pessimism pays.

Sequence risk: the retiree's problem

Averages hide one more cruelty, and it matters most exactly when the money matters most. Two retirees can earn the identical 7% average real return over thirty years and end up with wildly different outcomes — depending on when the bad years arrive.

If the crashes come early in retirement, while you are withdrawing to live on, you sell shares at the bottom to pay bills, permanently shrinking the base that later recoveries compound on. If the same crashes come late, after decades of growth, they barely dent the plan. This is sequence-of-returns risk, and it is why the years just before and after retirement are the most dangerous in an investor's life — not because returns are worse, but because withdrawals turn volatility into permanent loss.

The defense is unglamorous: keep a few years of spending in boring, stable assets as you approach retirement, so a crash never forces you to sell stocks at the worst moment. The best return is sometimes the one you protect, not the one you chase.

The number is still extraordinary

None of this is an argument against index funds. Quite the opposite. A 4–7% real return, earned by doing essentially nothing, with fees near zero, remains the best deal available to an ordinary investor. Every alternative — stock picking, market timing, expensive funds — has to clear a bar that almost none of them clear, which is why the data on active management is so grim.

The honest pitch for index funds was never "10% a year." It was always something quieter: a reasonable share of the economy's growth, captured cheaply, compounded patiently, by someone who understood exactly what the number meant. Now you do.

And there is a final footnote worth adding: the investor who earns 7% real for thirty years without panic-selling once will beat almost everyone who chased more. The return was never the hard part. Sitting still was.

That is the real return. It was never the headline. It was always the footnotes.