<prompt> Human: I understand that past market behavior is not a predictor of future market behaviors. That said.I am trying to weigh the cost benefits of this particular investment strategy. I seek to understand what the realist outcome of that strategy would have been had I put 1000 into an SP 500 index fund 16 years ago and continued to put 100yr into it. Adjusted for inflation on the US dollar as based on the CPI how much would it be worth today? I tried using Google finance and Yahoo finance but those sites work are confusing. When I searched information on SP 500 index funds performance, I found mostly generic articles. Moreover, all them spoke of the virtues of SP 500 index funds, and how the money invested one year would be worth x amount this year. However, none of them is clear; was it adjusted for inflation? Alternatively, how an SP 500 Index fund performed in comparison to the market. When I research investment companies SP 500 index funds, they swap around the fund every so often that the best you can get is like a two or 3-year history of performance. Meanwhile the company that I use for my investment account has this handle little tool to measure if I am on track for retirement but it keeps recommending using their investment strategy. This is a mix of domestic bonds and stocks and investment in foreign markets. Frankly, I am not convinced their recommendation is out of a fiduciary responsibility to me. I would appreciate it if there was an excel sheet or a good website that I can use for these kinds of calculations. Bonus if I can use the numbers from my own retirement account to determine how it performed in comparison.Edited for update.Update. So my question is not clear and it was pointed out that my starting point matters. So here goes. Starting in 2010, what would have been my REAL return on an SP 500 Index Fund, starting with 1000 and contributing 100yr till now.  <response>: Assume the following: You put 1000 into SPY, a popular SP 500 ETF on 12312000. You then put a hundred additional dollars into SPY on the last day of each year. You reinvested your dividends. You were able to buy fractional shares. You had no transaction costsBetween 123100 and today, you would have invested 2500. As of right now, youd own about 24.3 shares of SPY, with a fair market value of 5362.That represents a 6.58 annual return over that 16-year period. Inflation has been more like 1-2 in that same time frame. 