$100 a month in the S&P 500 for 10 years would be worth $27,282 today
120 monthly purchases of SPY at each month-end close from October 2016, valued at the October 14, 2026 close with dividends reinvested. The lump sum puts the same total in at the October 2016 close. Excludes taxes and inflation.
$100 or $500 a month in the S&P 500, by how long you invested
| Investing for | $100 a month paid in | $100 a month today | $500 a month today | Same total as a lump sum |
|---|---|---|---|---|
| 5 years From October 2021 | $6,000 | $9,399 | $46,997 | $10,750 |
| 10 years From October 2016 | $12,000 | $27,282 | $136,409 | $50,877 |
| 15 years From October 2011 | $18,000 | $60,413 | $302,063 | $143,331 |
| 20 years From October 2006 | $24,000 | $113,911 | $569,553 | $193,217 |
| 25 years From October 2001 | $30,000 | $177,713 | $888,563 | $342,303 |
Month-end closes adjusted for splits and dividends, through the October 14, 2026 close. Source: Yahoo Finance chart API, monthly close adjusted for splits and dividends. Excludes taxes, fees and inflation. Methodology
Past returns don't repeat. What does the price assume now?
These tables show what already happened. A buyer today gets the next ten years, and the price already reflects what the market expects. The reverse DCF calculator shows the growth today's price implies, so you can judge whether it is realistic.
Frequently asked questions
If I invest $100 a month in the S&P 500, how much will I have?
Over the last 10 years, $27,282 from $12,000 paid in. Over the last 25 years, $177,713 from $30,000. Those are real SPY prices with dividends reinvested; the future can be better or worse.
What about $500 a month?
Results scale with the amount: $500 a month for the last 10 years would be worth about $136,409 from $60,000 paid in.
Is a lump sum better than monthly investing?
In a rising market, usually yes, because money invested earlier has longer to grow. Putting the same $12,000 in all at once in October 2016 would be worth $50,877. Monthly investing wins when prices fall after you start, and it is how most people invest from a salary anyway.
How is this calculated?
One purchase at each month-end close of SPY, an S&P 500 index fund, using prices adjusted for splits and dividends, valued at the latest close. It ignores fund fees beyond SPY's own, taxes and inflation. Our price data starts in January 2000, so the longest window is about 26 years.
The math is easy. The macro is hard.
The calculator shows the arithmetic. Members get the monthly call that decides which inputs matter, plus written breakpoints when the facts move. $39/month or $249/year.
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