Investing $1,000 a month in the S&P 500 (a list of large US companies whose combined share price is tracked) for 20 years ended at a median of $647,862. The median is the middle result when we rank every start month, meaning the month of the first purchase. The plan that started in November 2006 ended at $1,118,582. That ranks sixth highest of 166, so it sits near the top of the range.
We bought SPY (the S&P 500 ETF), a fund that trades on a stock exchange like a single share and holds the shares in the index. We counted dividends, the cash that companies pay their shareholders.
What if you invest $1,000 a month? It means buying $1,000 of a fund on a set day each month, whatever its price.
In SPY, the S&P 500 ETF, the median 20-year plan ended at $647,862 from $240,000 paid in, with dividends (cash paid to shareholders) counted. The latest plan, started in November 2006, ended at $1,118,582, sixth highest of 166 start months.
Of 286 ten-year plans, 13 ended below the money paid in. All 166 twenty-year plans and all 46 thirty-year plans ended above it.
In the latest plans, money paid in made up 44.8% of the 10-year result, 21.5% of the 20-year result, and 15.0% of the 30-year result. The rest was growth.
What does investing $1,000 a month mean?
Investing $1,000 a month means buying $1,000 of a fund on a set day each month. Over 10, 20 and 30 years, that is 120, 240 and 360 purchases. The money paid in is $120,000, $240,000 and $360,000.
This habit is called dollar-cost averaging. Our comparison of a lump sum against spreading money in tests it against paying everything at once.
The rules of our test:
Buy day: the first trading day of each month, meaning the first day the stock exchange is open. The price is that day's closing price, the last price of the day.
Dividends: we reinvest them, meaning they buy more of the fund. Our price data already counts them.
Fractions of a share: allowed.
Value: we measure it on the last trading day of the month of the final purchase.
Median: the middle result when the start months are ranked. With an even count, it is the average of the two middle results.
Costs: we use SPY's price as quoted. We leave out taxes and dealing charges, the fees for each trade.
What did $1,000 a month become over 10, 20 and 30 years?
We wrote this on 11 November 2026. The price record runs to 10 November 2026, but we valued each plan on 30 October 2026, the last trading day of October.
The latest plan of each length is the one with the most recent start month. Each made its first purchase on the first trading day of November, in 2016, 2006, and 1996, and its last purchase on 1 October 2026.
The table shows, for each plan length, the money paid in, the latest plan, and the median, lowest, and highest results across all start months.
Plan length | Money paid in | Latest plan | Median start month | Lowest start month | Highest start month |
|---|---|---|---|---|---|
10 years | $120,000 | $267,660 | $202,221 | $81,438 | $288,043 |
20 years | $240,000 | $1,118,582 | $647,862 | $483,527 | $1,151,182 |
30 years | $360,000 | $2,400,899 | $2,154,210 | $1,734,336 | $2,480,929 |
$1,000 a month into SPY with dividends counted, bought on the first trading day of each month and valued on the last trading day of the final purchase month. The latest plan began in November 2016, 2006 and 1996 and was valued on 30 October 2026. Start months run from February 1993: 286 ten-year, 166 twenty-year and 46 thirty-year plans. Source: YX Insights price data
At 20 years, the latest plan's $1,118,582 sits just under the highest result of $1,151,182 and well above the median of $647,862. At 10 years, the latest plan ranks 22nd of 286. At 30 years, it ranks 6th of 46.
On the same dates, a plan of $500 a month ends at half of each figure. Our guides for $500 a month for 20 years and $100 a month for 10 years use other start dates, valuation dates or price records, so their figures differ.
How much came from payments and how much from growth?
Growth is the ending value minus the money paid in. In the latest 10-year plan, growth was $147,660, which is 55.2% of the $267,660. Payments were the other 44.8%.
In the latest 20-year plan, growth was $878,582, or 78.5%, while payments were 21.5%. In the latest 30-year plan, growth was $2,040,899, or 85.0%, while payments were 15.0%.
Source: YX Insights price data
Payments are a smaller share of the ending value as the plan gets longer. Early payments stay invested for more years, so their gains earn gains of their own.
How did the yearly rate compare across the three plans?
A money-weighted rate is the single yearly rate that fits every purchase, counting each $1,000 from the day it went in. For the three latest plans, it was 15.3% over 10 years, 13.6% over 20 years, and 10.7% over 30 years.
The three plans cover different years: 2016 to 2026, 2006 to 2026, and 1996 to 2026. Each rate reflects its own stretch of history, so the gaps do not show an effect of plan length.
How much did the start month matter?
A plan can start in any month. The first full month in SPY's record is February 1993, because the record begins on 29 January 1993. That allows 286 ten-year plans, starting from February 1993 to November 2016. It allows 166 twenty-year plans, starting from February 1993 to November 2006.
Only 46 thirty-year plans fit, all starting from February 1993 to November 1996. A thirty-year plan needs 30 years of prices. These plans overlap, so they are not independent tests. They cover one stretch of history.
Source: YX Insights price data
The chart shows each result as a multiple of the money paid in. At 10 years, the lowest start month ended at 0.68 times the money paid in, the only bar below the dashed line at 1.00.
At 20 years, the lowest result was $483,527, from a February 1993 start, which is 2.01 times the money paid in. The median was $647,862. The highest was $1,151,182, from a June 2006 start.
At 30 years, the lowest was $1,734,336, from a November 1993 start. The median was $2,154,210. The highest was $2,480,929, from a June 1996 start.
At 20 years, the highest result was 2.4 times the lowest, against 3.5 times at 10 years. The 30-year plans all started within one short stretch, so their range is narrow. The 1.4 times at 30 years rests on that stretch and cannot be compared with the 10-year figure.
Can a monthly plan end below what you paid in?
At 10 years, yes. Of the 286 ten-year plans, 13 ended below the $120,000 paid in.
Their start months fall between November 1998 and July 2000. The lowest, from a March 1999 start, was worth $81,438 on 27 February 2009.
Source: YX Insights price data
All 166 twenty-year plans and all 46 thirty-year plans ended above the money paid in. A plan can still sit below it on the way. In the latest 20-year plan, 30 month-ends between January 2008 and August 2010 showed a value below the money paid in. At the end of February 2009, $28,000 paid in was worth $16,382.
The latest 30-year plan had 30 such month-ends, between September 2001 and July 2009. The latest 10-year plan had none.
What does the test leave out?
The figures are in dollars of the day, before inflation. A dollar paid in 1996 bought more than a dollar paid in 2026. Our guide to how inflation erodes savings shows the effect.
The test covers one fund over one record. Our price record starts in 1993, so we cannot test earlier decades. We do not fill the gap with figures from elsewhere. The test makes no forecast.
Our guide to $10,000 in the S&P 500 ten years ago covers a single payment.
In SPY's record, the median 20-year plan of $1,000 a month turned $240,000 into $647,862, while 13 of 286 ten-year plans ended below the money paid in.
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Common questions about investing $1,000 a month
How much is $1,000 a month for 20 years worth?
It was worth a median of $647,862 in SPY, the S&P 500 ETF, from $240,000 paid in, across 166 start months with dividends counted. Results ran from $483,527 to $1,151,182. The latest plan ended at $1,118,582 on 30 October 2026, sixth highest. These are sums on past prices, not a forecast.
How much is $1,000 a month worth after 30 years?
The latest 30-year plan in SPY ended at $2,400,899 on 30 October 2026, from $360,000 paid in across 360 purchases. The median was $2,154,210. Only 46 start months fit our price record, running from February 1993 to November 1996, so the 30-year range rests on a narrow stretch of history.
Can you lose money investing $1,000 a month in the S&P 500?
Yes, over 10 years. Of 286 ten-year plans in SPY, 13 ended below the $120,000 paid in, with start months from November 1998 to July 2000. All 166 twenty-year plans and all 46 thirty-year plans ended above the money paid in. Their values still dipped below the money paid in along the way.
How much is $1,000 a month worth after 10 years?
The latest 10-year plan in SPY paid in $120,000 and ended at $267,660 on 30 October 2026. Across 286 start months, the median was $202,221. The lowest was $81,438, from a March 1999 start. The highest was $288,043, from a January 2012 start. None of this is a forecast.
DISCLAIMER: This article is intended for educational purposes only. Any information or analysis in this note does not constitute an offer to sell or a solicitation of an offer to buy any securities. Nothing in this note is intended to be investment advice, nor should it be relied upon to make investment decisions. Any opinions, analyses, or probabilities expressed in this note are those of the author as of the note's date of publication and are subject to change without notice.
