Stocks

S&P 500 Millionaire Calculator

How long until an S&P 500 index fund makes you a millionaire—and how much would you need to invest each month to get there by a target date? Adjust the return to test cautious and optimistic scenarios.

Last reviewed on October 4, 2026.

Your Investment Plan

S&P 500 with dividends averaged about 10% a year from 1928–2025 (before inflation)
Used for the "monthly needed" result

Popular S&P 500 ETFs:

  • VOO (Vanguard) - 0.03% expense ratio
  • IVV (iShares) - 0.03% expense ratio
  • SPY (State Street) - about 0.09% expense ratio
27 years, 4 months
Until you're an S&P 500 millionaire
$1,220
Monthly Needed for $1M in 20 Years
$174,000
Total Invested
$830,758
Market Gains

Why the S&P 500 Works

The S&P 500 tracks about 500 of the largest U.S. companies, weighted by market value. Companies that shrink or no longer qualify are replaced, so one low-cost fund gives you broad diversification. Low fees mean more of the return stays invested.

Layer Index Investing Into Your Plan

The S&P 500 can be held inside a 401k, IRA, or taxable brokerage. See how account choice affects your timeline.

401k Calculator Portfolio to $1M

Why Many Investors Use S&P 500 Index Funds

Warren Buffett has long argued that most people are best served by a low-cost S&P 500 index fund. In his 2013 letter to Berkshire Hathaway shareholders he wrote that his instructions for his wife's inheritance are to put 10% in short-term government bonds and 90% in a very low-cost S&P 500 index fund. The appeal: broad diversification, very low fees and no need to pick stocks.

What Is the S&P 500?

The S&P 500 is an index of roughly 500 large U.S. companies chosen by a committee at S&P Dow Jones Indices based on size, liquidity and profitability, and weighted by market value. An S&P 500 fund (such as VOO, IVV or SPY) owns all of them, including:

Because it is weighted by market value, the largest companies make up a big share of the index, so it is less diversified than "500 stocks" suggests.

Historical Returns: What the Data Shows

Including reinvested dividends, the S&P 500 returned about 10.0% a year (compound average) from 1928 to 2025 and about 10.6% a year since the 500-stock index launched in 1957, according to Aswath Damodaran's data at NYU Stern. After inflation, that is roughly 6.5–7% a year. That long-run average includes:

Individual years vary enormously, from −36.5% in 2008 to +32% in 2013. Past returns do not guarantee future ones, so it is sensible to also test 7–8%.

The Math: How $500 a Month Becomes $1 Million

Starting with $10,000, investing $500 a month and earning 10% a year (compounded monthly):

Early on, your contributions do most of the work. Later, growth takes over: by the time you reach $1M in this example, about 83% of the balance came from market returns.

How Much to Invest Monthly to Reach $1 Million

Starting from $0, investing a fixed amount every month:

Why Index Funds Usually Beat Active Funds

S&P Dow Jones Indices' SPIVA scorecards have found that roughly nine in ten actively managed U.S. large-cap funds trailed the S&P 500 over 15-year periods.

1. Fees compound. Index funds tracking the S&P 500 charge as little as 0.03% a year; many active funds charge far more. Example: $500 a month for 30 years grows to about $1,130,000 at 10%, but only about $825,000 if fees and trading costs drag the return down to 8.5%—a gap of about $305,000.

2. Consistently picking winners is hard. Few managers outperform for decades, and it is hard to identify them in advance.

3. Tax efficiency. Index funds trade little, so they tend to distribute fewer taxable capital gains.

VOO vs. IVV vs. SPY

All three track the S&P 500; differences are small.

Fund Provider Expense Ratio Notes
VOOVanguard0.03%Low cost for buy-and-hold
IVVBlackRock (iShares)0.03%Low cost for buy-and-hold
SPYState Street~0.09%Most heavily traded; popular with traders

Check current expense ratios on the providers' sites. Mutual-fund versions (such as Fidelity's or Schwab's S&P 500 index funds) work just as well inside many 401(k) plans. These are examples, not recommendations.

Common Mistakes

Living Off an S&P 500 Million

The "4% rule" from Bengen's 1994 research and the 1998 Trinity study suggests withdrawing about 4% in the first year ($40,000 from $1M) and adjusting for inflation afterwards; historically that lasted at least 30 years in most periods for stock-heavy portfolios. It is not a guarantee: a bad market early in retirement can deplete a portfolio much faster, and a 100% stock portfolio can fall by a third or more in a single year. Many retirees hold some bonds or cash for that reason.

Example: retire at 60 with $1.2 million → 4% = $48,000 in the first year ($4,000/month), plus Social Security (the average retired-worker benefit is roughly $2,000/month) ≈ $6,000/month before taxes.

How to Start

  1. Choose an account: a 401(k) or IRA if eligible, or a taxable brokerage account.
  2. Fund it with whatever you can, even $100. Many brokers allow fractional shares.
  3. Buy a low-cost S&P 500 fund (or a total-market fund).
  4. Automate monthly investing.
  5. Turn on dividend reinvestment.
  6. Review once or twice a year rather than reacting to daily moves.

S&P 500 Millionaire Timeline by Age

Starting from $0 with $500 a month at 10%, reaching $1M takes about 29 years:

Projections assume a steady return, which markets never deliver. See our disclaimer.

Frequently Asked Questions

With $10,000 to start and $500 a month at a 10% average return, about 27 years and 4 months. With $1,000 a month it takes about 21.7 years; starting with $50,000 and $500 a month, about 22.8 years. At a more cautious 8%, add several years.

Starting from $0, about $4,880 a month at a 10% average return, or about $5,470 a month at 8%. A lump sum would need to be about $386,000 at 10% (or $463,000 at 8%). Over just 10 years, results can differ a lot from the average.

It depends on how many years you have: at a 10% average return, about $440 a month for 30 years, $750 for 25 years, or $1,320 for 20 years. At 8%, about $670, $1,050 and $1,700 respectively.

At the historical average of about 10% a year, $1 million would grow to roughly $2.6 million in 10 years; at 7% it would be about $2.0 million. Ten-year results have ranged from losses to far above average, so treat this as an estimate.

About 10% a year compounded, including dividends, from 1928 to 2025 (about 10.6% since 1957), based on NYU Stern's Damodaran data. After inflation it is roughly 6.5–7%. Single years ranged from −36.5% (2008) to +32% (2013) in recent decades.

For many long-term investors it is a simple, low-cost core holding: broad diversification, fees as low as 0.03% and no stock picking. It is still 100% U.S. large-company stocks and can fall sharply, so it should match your time horizon and risk tolerance.

They hold the same index. VOO and IVV charge 0.03% a year; SPY charges about 0.09% and is mainly favored by active traders for its liquidity. For buy-and-hold investors the cheapest fund available at your broker is usually fine.

It falls with the market. The index dropped about 57% from 2007 to 2009 and regained its previous high in 2013; the 2020 COVID drop of about 34% was recovered within about five months of the bottom. Selling during a crash locks in losses.

Possibly. The 4% rule suggests about $40,000 in the first year, adjusted for inflation; together with Social Security that can support a modest retirement. Because an all-stock portfolio can fall sharply early in retirement, many retirees hold some bonds or cash too.

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