What Is the S&P 500 Return?
The S&P 500 is a stock market index of about 500 of the largest companies listed in the United States, weighted by their market value. It is the most common yardstick for "the stock market", and many index funds and ETFs simply copy it. The S&P 500 return is how much an investment that follows the index gained or lost over a period.
There are several ways to measure that return, and this calculator shows four of them side by side:
- Price only: how much the index itself rose or fell, ignoring the dividends the companies paid.
- With dividends reinvested: the total return if every dividend was used to buy more of the index. Over long periods dividends are a large part of the stock market's return.
- After inflation, price only: the price return measured in constant dollars, using the U.S. consumer price index, so it shows the buying power you gained.
- After inflation, with dividends: the total return in constant dollars, often called the real total return.
Each one is shown two ways. The total return is the change over your whole period. The annualized return is the steady yearly rate that would give the same result, which makes periods of different lengths easy to compare.
How to Calculate the S&P 500 Return
The calculator follows your money month by month along each of the four index series. The value at any month is your investment multiplied by how much the series grew since your start month:
The total return is the growth over the whole period, and the annualized return spreads it over the years:
Where m is the number of months from the start month to the end month.
Example
$1,000 invested in December 2025 with dividends reinvested was worth $1,093.36 by June 2026, 6 months later:
- Total return = $1,093.36 ÷ $1,000 − 1 = 9.34%
- Annualized return = (1 + 9.34%)12/6 − 1 = 19.54%
For periods shorter than a year, the annualized return assumes the same pace would continue for a full year, so it can look much bigger (or smaller) than the total return. Over long periods it is the better number to compare.
How to Use the S&P 500 Return Calculator
"If I had put $1,000 into the S&P 500 in December 2025, what would it be worth by June 2026, with dividends and after inflation?" This calculator answers that.
Let's enter the numbers for this example in each box. They are already filled in when the calculator opens, so you can follow along and then change any box to your own period and amount.
- Start Month and Year: Pick December and 2025, which is the month your investment begins. The earliest you can pick is Jan 1871.
- End Month and Year: Pick June and 2026, which is the month you measure what the investment is worth. It must be after the start month. The latest month with complete data is shown in the "Data available" badge (Jan 1871 – Jun 2026); later months are greyed out.
- Investment: Enter 1,000, which is the amount you invest in the start month. It must be greater than 0.
Under the boxes, the calculator tells you how many months you selected: 6 months for this example.
How to Choose the Months
The calculator measures the change from the start month to the end month, so the number of months is the difference between them. The start month is the month before your period begins. A few examples:
- One full year: use the same month for start and end. For the year after the November 2020 U.S. election, pick December 2020 to December 2021: 12 months.
- A calendar year: use December for both. For 2023, pick December 2022 to December 2023. This comes close to the S&P 500's published calendar-year return.
- One month: pick the month before as the start. For August 2023, pick July 2023 to August 2023.
- Year to date: pick December of last year as the start and the newest month as the end. That's what the calculator shows when it opens.
Each month's figure is the average of that month's daily closing prices, not the price on one exact day, so results can differ a little from returns measured between two exact dates.
Calculate and Reset
Click Calculate to see your results. If a box has a problem, such as an end month that isn't after the start month, a message pops up under that box instead. With the default numbers you get:
- Your Results: a short summary in words: $1,000 grew to $1,093.36 with dividends reinvested, a gain of 9.34% (19.54% a year), and 6.09% (12.56% a year) after inflation.
- Value with dividends reinvested: the headline number, $1,093.36.
- Annualized returns: all four side by side: 18.18% price only, 19.54% with dividends, 11.28% after inflation, and 12.56% after inflation with dividends.
- Returns table: the annualized return, total return and final value for each of the four ways. The final values here range from $1,054.89 (after inflation, price only) to $1,093.36 (with dividends).
- Chart: the value of your investment month by month, one line for each of the four ways.
- Yearly and Monthly table: the value at the end of each year (or month) for all four ways. Use Download CSV to open it in a spreadsheet.
- Share Results: a link that opens this calculator with your months and amount filled in. Copy it, or share it on Facebook or X.
Amounts of $1 million or more are shortened, for example $8.38M. Click Reset to put every box back to its default (December 2025 to June 2026, $1,000) and show the default results again.
Data Source
All data comes from Professor Robert Shiller's monthly S&P 500 series, which goes back to 1871. For the methodology, see chapter 26 of his book Market Volatility (Cambridge, MA: MIT Press, 1989). Dividend and inflation figures are published a few months after prices, so the calculator runs to the newest month that has all of them. Results don't include taxes, fees or trading costs, and past returns don't guarantee future results.