Introduction
This S&P 500 calculator shows what your money would have done if you had invested in the S&P 500 index in the past. Pick a start date and an end date, type in how much you put in, and see what your investment would be worth today.
The tool uses real S&P 500 return data going back to 1928. You can add a lump sum, monthly contributions, or both. Turn on dividend reinvesting to see total return. Turn on inflation to see what your money is really worth in today's buying power.
You can also:
- Compare two time periods side by side
- See lump sum investing versus dollar-cost averaging
- Find out how much waiting to invest would have cost you
- Compare the S&P 500 to savings accounts, bonds, and gold
- Read a year-by-year breakdown and step-by-step math
Past returns do not promise future returns. But looking at history helps you understand how compounding, dividends, and time work together to grow money in the stock market.
How to use our S&P 500 Calculator
Pick a start date and end date, type how much you invest, and pick your settings. The calculator shows your ending balance, total gain, total return, yearly return (CAGR), a growth chart, and a year-by-year table.
Quick Date Ranges: Click a button like "Last 10 Years" or "Full History" to fill in the dates fast. Your dollar amounts stay the same.
Start Date (Month / Year): Choose the month and year you put your money in. Data starts in 1928.
End Date (Month / Year): Choose the month and year you want to stop. It must come after the start date. Use the date duration calculator if you want to check how long that stretch really is.
Initial Lump Sum Investment: Type the amount you invest on day one, from $1 to $100,000,000. For a plain one-time deposit, the lumpsum calculator covers the same idea at a fixed rate.
Monthly Contribution: Type the amount you add at the start of each month. Leave it blank or use $0 if you only invest once.
Reinvest Dividends (Total Return): Turn this on to count dividends put back into the market. Turn it off to see price change only. Our DRIP calculator and dividend calculator go deeper on reinvested payouts.
Adjust for Inflation (Real Returns): Turn this on to see what your money is worth in start-date dollars, using CPI inflation. The CPI inflation calculator shows the same price data on its own.
Show Annualized (CAGR) Return: Turn this on to see your average return per year instead of just the total.
Overlay Benchmarks: Check the boxes to add a savings account, 10-year Treasury bonds, or gold to the chart so you can compare them to the S&P 500. See also the treasury bond calculator.
Savings APY: Type the yearly rate for a high-yield savings account or CD, from 0% to 25%. This only matters if you check the savings box. The HYSA calculator, CD calculator, and APY calculator help you pick a realistic rate.
Add Comparison Scenario B: Turn this on to test a second plan next to your first one. A side-by-side table shows the difference.
Scenario B Start and End Dates: Pick the month and year range for your second plan.
Scenario B Lump Sum and Monthly: Type the starting amount and monthly amount for your second plan.
Scenario B Dividends and Inflation: Turn these on or off to change how Scenario B is figured out.
Delay Starting By (What If I Had Waited): Type a number and pick months or years. The tool shows how much waiting would have cost you by the same end date.
Calculate and Reset: Click Calculate to see your results. Click Reset to put every input back to its default.
What Is the S&P 500?
The S&P 500 is a stock market index. It tracks the share prices of about 500 of the largest public companies in the United States. Names like Apple, Microsoft, and Johnson & Johnson are in it. Together these companies make up roughly 80% of the value of the whole U.S. stock market, so people use the index as a quick way to see how American stocks are doing.
The index is market-cap weighted. That means bigger companies count more. If a giant company rises 1%, it moves the index far more than a small company rising 1%. Most people own it through a low-cost fund, which you can model with the index fund calculator or the mutual fund calculator.
Price Return vs. Total Return
There are two ways to measure S&P 500 growth:
- Price return counts only the change in share prices.
- Total return counts price changes plus dividends that you reinvest. Dividends are cash payments companies send to shareholders.
Total return is almost always higher. Over long periods, reinvested dividends have added roughly 2% per year. That small gap grows huge after a few decades because of compounding. To see how much income a fund throws off today, try the dividend yield calculator.
Historical Returns
Since 1928, the S&P 500 has returned about 10% per year on average with dividends reinvested. But no single year is average. The index gained over 45% in 1954 and lost over 43% in 1931. Stocks fell more than 36% in 2008, then more than doubled in the ten years after. Big swings are normal. A quick way to sense the power of a 10% average is the Rule of 72 calculator, which estimates how long money takes to double.
Why Inflation Matters
Inflation eats away at what your money can buy. A real return is your return after subtracting inflation. If stocks gain 10% and prices rise 3%, your real gain is about 7%. Looking at real returns tells you how much richer you actually got. The inflation calculator and US inflation calculator show past price changes in dollar terms.
CAGR: The Yearly Average
CAGR stands for compound annual growth rate. It is the smooth, steady yearly rate that would take your starting money to your ending money. It is a fair way to compare two investments over different time spans. When you add money every month, the math changes slightly and uses a money-weighted rate (also called IRR), because each dollar is invested for a different length of time. The IRR calculator and ROI calculator break those two measures apart.
Lump Sum vs. Dollar-Cost Averaging
A lump sum means putting all your money in at once. Dollar-cost averaging (DCA) means investing a set amount each month. Because markets go up more often than down, lump sums usually win over long stretches. But DCA helps when a market falls right after you start, since your later buys pick up shares at lower prices. DCA is also how most people really invest, through paychecks and retirement plans such as a 401(k) or a Roth IRA.
Time in the Market
Starting sooner is one of the strongest advantages an investor has. Delaying just a few years can cut a final balance by a large amount, because the earliest dollars have the most years to compound. Missing a handful of the market's best days can also drag down long-run results, which is why many investors stay invested instead of trying to guess tops and bottoms. If you are mapping out a long horizon, the investment calculator, future value calculator, and retirement calculator pair well with this tool.
Things to Keep in Mind
- Past returns do not promise future returns.
- Real-world results also depend on fees, taxes, and the fund you use to track the index. Check the drag from costs with the expense ratio calculator and the bill on gains with the capital gains tax calculator.
- The S&P 500 holds only large U.S. companies. It leaves out small caps, bonds, and foreign stocks.
- Money you may need within a few years is usually not a good fit for stocks. Park short-term cash where an emergency fund calculator says it belongs instead.
- When you sell, the stock profit calculator shows your gain after commissions.