What If You Had Invested in the S&P 500?

A what-if investment calculator replays history: it shows what money put into the S&P 500 in a past year would be worth by June 2026.

What would it be worth today?

Amount

How often

Start year

Your $1,000 became about

$8,518

Up: Your money grew ×8.5

$1,000 put in once in January 2006 was worth about $8,518 by June 2026, a gain of about $7,518.

S&P 500
Money you put in
Savings comparison
Extra growth

Month-by-month values behind the chart
Month	S&P 500, dividends reinvested	Money you put in	Savings comparison (Treasury bills, a stand-in for a high-yield savings account)
January 2006	$1,000	$1,000	$1,000
June 2006	$987	$1,000	$1,019
November 2006	$1,102	$1,000	$1,040
April 2007	$1,171	$1,000	$1,061
September 2007	$1,206	$1,000	$1,082
February 2008	$1,100	$1,000	$1,097
July 2008	$1,030	$1,000	$1,105
December 2008	$728	$1,000	$1,110
May 2009	$758	$1,000	$1,111
October 2009	$907	$1,000	$1,111
March 2010	$986	$1,000	$1,112
August 2010	$939	$1,000	$1,112
January 2011	$1,116	$1,000	$1,113
June 2011	$1,128	$1,000	$1,114
November 2011	$1,084	$1,000	$1,114
April 2012	$1,236	$1,000	$1,114
September 2012	$1,298	$1,000	$1,114
February 2013	$1,373	$1,000	$1,115
July 2013	$1,527	$1,000	$1,115
December 2013	$1,669	$1,000	$1,115
May 2014	$1,758	$1,000	$1,115
October 2014	$1,817	$1,000	$1,116
March 2015	$1,967	$1,000	$1,116
August 2015	$1,945	$1,000	$1,116
January 2016	$1,846	$1,000	$1,116
June 2016	$2,023	$1,000	$1,117
November 2016	$2,120	$1,000	$1,119
April 2017	$2,330	$1,000	$1,121
September 2017	$2,482	$1,000	$1,126
February 2018	$2,714	$1,000	$1,132
July 2018	$2,824	$1,000	$1,140
December 2018	$2,616	$1,000	$1,150
May 2019	$2,933	$1,000	$1,162
October 2019	$3,084	$1,000	$1,172
March 2020	$2,769	$1,000	$1,179
August 2020	$3,570	$1,000	$1,180
January 2021	$4,021	$1,000	$1,181
June 2021	$4,519	$1,000	$1,181
November 2021	$5,003	$1,000	$1,181
April 2022	$4,734	$1,000	$1,182
September 2022	$4,179	$1,000	$1,190
February 2023	$4,460	$1,000	$1,210
July 2023	$4,961	$1,000	$1,235
December 2023	$5,190	$1,000	$1,262
May 2024	$5,833	$1,000	$1,290
October 2024	$6,490	$1,000	$1,318
March 2025	$6,402	$1,000	$1,342
August 2025	$7,257	$1,000	$1,365
January 2026	$7,885	$1,000	$1,387
June 2026	$8,518	$1,000	$1,408

You put in$1,000
Gain$7,518
Per year11.1% a year

How Does the What-If Calculator Work?

The what-if calculator works as a replay of S&P 500 history with three moving parts: when you start, how often you add money, and what the index did month by month.

Ending value = each deposit × (the index level in June 2026 ÷ the index level in the month you put it in), added up.

Pick an amount, a start year and how often you add money. A start year puts your first deposit in January of that year.
We price each deposit at that month's average S&P 500 level and carry it to June 2026. Dividends are reinvested, so the index we use already counts them.
The savings comparison puts the same deposits into 3-month Treasury bills, compounding monthly at the rate published for each month.
The yearly rate is the single rate that turns your deposits into the ending value, counting when each one went in. For a one-time amount it is the familiar compound annual growth rate.
Weekly deposits are added once a month (52 deposits a year spread over 12 months), because our data is monthly.
Today's dollars multiplies each amount by the Consumer Price Index in June 2026 divided by the index in the month it was put in.

What $1,000 put in once in January would be worth in June 2026, by start year. Dividends reinvested. History, not a forecast.
Start	Ending value	Multiple	Per year	Savings comparison
January 1996	$20,759	×20.8	10.5%	$2,014
January 2006	$8,518	×8.5	11.1%	$1,408
January 2016	$4,614	×4.6	15.8%	$1,262

Reading the Chart

What do the pins on the chart mean?

The pins on Rapunzl's chart mark the biggest peak-to-trough falls of the S&P 500 inside the window you pick, found in the data rather than typed in. For the default window the largest is a fall of 49% from October 2007 to March 2009. The index was back at its October 2007 level by August 2012, 4 years 10 months after the peak. The size is measured on monthly average prices, so it comes out smaller than the drop from the single highest day to the single lowest. A pin shows what the index did. What your own balance did depends on whether you were still adding money, which is why a one-time plan and a monthly plan get different cards.

Is the savings line a real savings account?

No, the savings line is not a real savings account, and the chart labels it that way. Rapunzl's savings line compounds the 3-month Treasury bill rate every month on the same deposit schedule as the stock line. We use it because the Federal Reserve publishes it back to January 1934, and we found no savings-account rate series that goes that far. Both follow short-term interest rates, but they are not the same product. Most savings accounts pay far less: the FDIC's national average savings rate is 0.37% as of September 2026. Before January 1934 there is no line at all.

Why might my result differ from other S&P 500 calculators?

Your result might differ from other S&P 500 calculators because each one makes different choices about prices, dividends and fees. Rapunzl's calculator prices every deposit at the monthly average level of the index, not the closing price on one day, so a January 2006 deposit uses the January average. That means calendar-year returns can differ from published year-end figures by a few points. The data is Robert Shiller's total-return series with dividends reinvested, and before 1957 it comes from the S&P Composite, a reconstructed predecessor of the S&P 500. Other calculators may start on a particular day, use price return without dividends, or take out fees, and each choice moves the answer.

Using the Calculator in Class

Project it and ask students to guess the ending value before you press go, then try three start years and compare. Ask why a start just before a fall, like October 2007, feels so different from one just after. The module below covers how stocks trade, and the posts show how teachers run the same idea with a simulator.

Questions about the what-if calculator

It would have grown to about $8,518 by June 2026, roughly 11.1% a year, with dividends reinvested. That window runs from January 2006, so it is a little over 20 years. The same $1,000 in the savings comparison (3-month Treasury bills) reached about $1,408. Amounts scale in proportion, so $100,000 over the same window would have become about $851,802. This is history, not a forecast, and the window includes a 49% fall. Start a different year and the answer changes: $1,000 put in during January 2016 reached about $4,614.

Divide the ending value by the starting value, then turn that into a yearly rate: (ending ÷ starting) raised to the power of 1 ÷ years, minus 1. For the default run, $8,518 ÷ $1,000 is 8.52 over 20.4 years, which is 11.1% a year. When you add money over time, the calculator finds the single yearly rate that makes every deposit, grown at that rate, add up to the ending value. Dividends are included: total return counts them as reinvested and price return doesn't. We use Robert Shiller's total-return series, with estimates for dividends from April 2026 on. Because it works from monthly average prices, calendar-year figures can differ from published year-end numbers by a few points.

Using this calculator's data and one-time deposits, $1,000 put in during January 2016 grew 15.8% a year through June 2026, or 12.1% a year after inflation. Starting January 2006, the figures are 11.1% a year and 8.3% a year after inflation. Starting January 1996, it was 10.5% a year. Each figure belongs to its window and end date, and a different start month gives a different number. They describe what happened, not what to expect.

Divide the total dollars you invested by the total shares you bought. Say you put $100 into a fund three times, at prices of $10, $8 and $12. You buy 10, 12.5 and 8.33 shares, 30.83 in all for $300, so your average cost is $9.73 a share. The plain average of the three prices is $10.00. Your cost came out lower because the same dollars buy more shares when the price is low. Choose "Every month" above to see this on real S&P 500 prices.

In this calculator's history, the lump sum has come out ahead, because the money spends more time in a market that rose over most of these windows. For the default start, $100 a month from January 2006 put in $24,600 and ended at about $117,668. The same $24,600 put in all at once that month ended at about $209,543. Across every start year from 1928 through 2021 (94 windows of at least 5 years, all ending in June 2026), the lump sum finished ahead. The comparison assumes you had the whole amount on day one, which most people don't. Most people add money from each paycheck rather than all at once. Results are historical and not a forecast.

No. The calculator replays what the S&P 500 did in the past and shows what your amount would have become. It can't tell you what comes next. The SEC's investor.gov site says a fund's past performance does not necessarily predict future results, and that applies here too. A replay also leaves out fund fees and taxes, and the default run includes a 49% fall from October 2007 to March 2009, so the good years come with the bad ones attached.

Want this in your school?

Rapunzl is a personal finance course with a real-time investing simulator, built for classrooms. Request a free demo, or pass this page to a teacher who would want it.

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Bring This And Much More To Your Child

Your child gets $10,000 in practice money to invest at real market prices, plus lessons on budgeting, credit and paying for college. They can work through all of it at home.

See Rapunzl For Parents

Sources. Robert J. Shiller (shillerdata.com): Monthly S&P Composite total-return index, January 1928 to June 2026. Prices are monthly averages, and dividends are reinvested. Source: BLS via FRED: Consumer Price Index for All Urban Consumers (CPI-U, series CPIAUCSL), from January 1947. Source: Board of Governors of the Federal Reserve System via FRED: 3-month Treasury bill secondary market rate (series TB3MS), from January 1934. Used as a stand-in for a high-yield savings account. Investor.gov (SEC): Mutual Funds, Past Performance: The SEC requires funds to tell investors that past performance does not necessarily predict future results. FDIC, National Rates and Rate Caps (savings, national deposit rate): as of 2026-09-21 (FDIC data date; checked 2026-10-12). Figures last checked October 12 2026.

What would it be worth today?

Your result

How Does the What-If Calculator Work?

Reading the Chart

What do the pins on the chart mean?

Is the savings line a real savings account?

Why might my result differ from other S&P 500 calculators?

Using the Calculator in Class

Questions about the what-if calculator

What if I had invested $1,000 in the S&P 500 20 years ago?

How do I calculate the S&P 500's historical return, and are dividends included?

What is the S&P 500's average annual return over the last 10 and 20 years?

How do I calculate my dollar-cost average?

How does investing monthly compare with investing a lump sum?

Is this a prediction of what I would earn?

Want this in your school?

Bring This And Much More To Your Child

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