What if I had invested $100 a month in Costco
Investing a fixed amount every month, whatever the price: that is dollar-cost averaging. Here is what this strategy would have done in Costco, depending on the year you started.
Since December 2003, Costco (a stock listed on Wall Street) grew 28-fold in dollar terms: an annualized return of +15.6% over nearly 23 years. For a monthly investor, almost every purchase was made below today's price: 99% of the 275 monthly buys since December 2003.
Data: Yahoo Finance monthly closing prices, up to date as of (latest update November 3, 2026) MethodAuthor: Yann Avondo
If I had invested $100 every month in Costco since January 2016, today I would have $41,908
Over the same period
Worst moment: −20.7% between March 2022 and December 2022. To get this result, you had to hold on without selling.
Costco at a glance
Costco runs membership-only warehouse clubs. Most of its profit comes from membership fees, a highly loyal model that has rewarded shareholders over time.
At the worst point, between May 2008 and February 2009, Costco gave up 40.6% in dollar terms; it took 2 years and 7 months to get back to its peak. Against the MSCI World, this calculator's yardstick (+7.0% a year in dollar terms over the same period), Costco left it far behind. Its best calendar year was 2021 (+50.7%), its worst 2008 (−24.7%); in all, 18 up years out of 22.
$100 a month in Costco, by start year
One contribution at the start of each month since January of the given year, valued at the latest price. Click a year for the full story.
| Start | Invested | Worth today | Multiple | Annual IRR |
|---|---|---|---|---|
| $2,300 | $2,468 | ×1.07 | +7.2% | |
| $3,500 | $4,020 | ×1.15 | +9.5% | |
| $4,700 | $6,374 | ×1.36 | +15.7% | |
| $5,900 | $8,764 | ×1.49 | +16.1% | |
| $7,100 | $11,832 | ×1.67 | +17.1% | |
| $8,300 | $15,708 | ×1.89 | +18.1% | |
| $9,500 | $20,591 | ×2.17 | +19.0% | |
| $10,700 | $26,530 | ×2.48 | +19.6% | |
| $11,900 | $33,910 | ×2.85 | +20.1% | |
| $13,100 | $41,908 | ×3.2 | +20.0% | |
| $14,300 | $50,372 | ×3.52 | +19.6% | |
| $15,500 | $60,657 | ×3.91 | +19.4% | |
| $16,700 | $71,881 | ×4.3 | +19.1% | |
| $17,900 | $85,310 | ×4.77 | +18.9% | |
| $19,100 | $101,040 | ×5.29 | +18.7% | |
| $20,300 | $121,741 | ×6 | +18.8% | |
| $21,500 | $146,552 | ×6.82 | +18.8% | |
| $22,700 | $165,690 | ×7.3 | +18.3% | |
| $23,900 | $186,824 | ×7.82 | +17.9% | |
| $25,100 | $210,608 | ×8.39 | +17.5% | |
| $26,300 | $237,710 | ×9.04 | +17.2% | |
| $27,500 | $268,349 | ×9.76 | +16.9% |
Lump sum or DCA in Costco?
Since January 2016, investing in Costco all at once (lump sum) multiplied the stake by ×6.37, +18.5% a year. Investing every month (DCA) multiplied the total contributions by ×3.2, an annual return (IRR) of +20.0%.
Here DCA did better: spreading the purchases avoided putting all the money in at the wrong time.
Frequently asked questions
How much would I have if I had invested $100 a month in Costco for 10 years?
Investing $100 every month since January 2016, $13,100 in total, would be worth about $41,908 today: an annual return (IRR) of +20.0% (price only, in the displayed currency).
What if I had started investing $100 a month in Costco in 2015?
Since January 2015, $14,300 invested in total would be worth about $50,372 today (IRR of +19.6% a year).
What if I had started investing $100 a month in Costco in 2020?
Since January 2020, $8,300 invested in total would be worth about $15,708 today (IRR of +18.1% a year).
Is investing monthly better than investing all at once?
Historically, investing a lump sum right away returns more in most cases, because markets rise more often than they fall. But monthly investing smooths the purchase price, protects against the worst timing and matches how people actually save: from their paycheck, month after month.
How is the annual return calculated?
With spread-out contributions, the multiple of the amount invested does not tell the whole story: the last dollars had only a few months to grow. The IRR (internal rate of return) is the average annual return that, applied to each contribution from its date, produces the final value.
Compare with
Before you have regrets
What this calculation does not tell you.
Hindsight bias
Picking Nvidia or Bitcoin today means picking known winners. Back then, nothing set them apart from hundreds of assets that went nowhere or vanished.
Holding on was the real test
The result assumes you never sold, including through the drawdowns shown above. Very few investors actually do.
The broad market, no bet required
The MSCI World never makes headlines, but it does not require guessing the winner. It is the fairest yardstick for any pick.
Method: past performance, computed from split-adjusted monthly closing prices (intra-month lows are smoothed out). Converted at each month’s exchange rate; no fees, no taxes. The MSCI World benchmark is the price index, excluding dividends. Sources: Yahoo Finance (prices, exchange rates, US Treasury bills), Eurostat (inflation), published regulated rates (Livret A). Not investment advice. NokxiHub.