So you want to amass a million dollars by retirement, and you'd like to get there by investing in an exchange-traded fund (ETF) -- a fund that trades like a stock. That's a fine plan (though some people might want to aim for more than a million dollars). There are more than 2,500 ETFs out there, so it's fair to find the thought of picking the best one, or a very good one, daunting. Here's a look at a solid contender for your long-term investing dollars, along with a bonus ETF. Image source: Getty Images. Meet the Vanguard Total Stock Market ETF When choosing an ETF, many people opt for the SPDR S&P 500 ETF (NYSEMKT: SPY), which is evident from the fund's No. 1 ranking among the biggest ETFs. It's a solid choice, offering roughly the same return as the S&P 500 index of about 500 of America's biggest companies, while charging a tiny annual fee of 0.0945%. Consider investing those long-term dollars in the Vanguard Total Stock Market ETF (NYSEMKT: VTI) instead, though. While the S&P 500 index focuses on large companies, with its constituents making up around 80% of the overall U.S. stock market's value, this ETF tracks the entire stock market. This means you'll be invested not only in all of the largest publicly traded companies in the U.S., but you'll also have your money distributed across medium-sized and small companies on the U.S. markets, too. Better still, the ETF's expense ratio (its annual fee) is a minuscule 0.03%. Here's a look at how these two ETFs have performed over the past five, 10, and 15 years: Average Annual Return Over: SPDR S&P 500 ETF Vanguard Total Stock Market ETF 5 years 18.14% 10.72% 10 years 16.3% 16.17% 15 years 10.6% 17.70% Data source: Morningstar.com. You can't quite compare these returns to the overall market, because each of the ETFs, in its way, is the market. Thanks to their very low fees, their returns will closely mirror the returns of the S&P 500 or the total U.S. stock market. To see how the Vanguard ETF (or the S&P 500-focused ETF, for that matter) would grow your money to a million dollars, check out the table below, which uses a somewhat conservative growth rate of 8%: Growing at 8% for: $5,000 Invested Annually $10,000 Invested Annually $15,000 Invested Annually 5 years $31,680 $63,359 $95,039 10 years $78,227 $156,455 $234,682 15 years $146,621 $293,243 $439,864 20 years $247,115 $494,229 $741,344 25 years $394,772 $789,544 $1.2 million 30 years $611,729 $1.2 million $1.8 million 35 years $930,511 $1.9 million $2.8 million 40 years $1.4 million $2.8 million $4.2 million Data source: calculations by author. A bonus ETF to consider If you'd like to aim even higher than average stock market returns, take a look at the Invesco QQQ Trust (NASDAQ: QQQ), which is made up of the 100 largest non-financial companies listed on the Nasdaq stock market, as measured by market capitalization. Among them you'll find many well-known names that have soared in recent years, such as: Alphabet Amazon.com Apple Meta Platforms Microsoft Nvidia Tesla And it also has plenty of other well-regarded smaller (but still quite big) companies, such as: Activision Blizzard Airbnb Costco Crowdstrike Datadog DocuSign Intuitive Surgical Palo Alto Networks Starbucks Zoom Video Communications Not surprisingly, then, the ETF sports an impressive track record: Average Annual Return Over: Invesco QQQ Trust 5 years 27% 10 years 22.1% 15 years 16.6% Data source: Morningstar.com. Indeed, according to the fund, it's "rated the best-performing large-cap growth fund (1 of 313) based on total return over the past 15 years by Lipper, as of Sept. 30, 2021." Its annual fee is also quite reasonable, at 0.20%. You would probably do quite well investing in any of the three ETFs mentioned above, and you don't have to pick just one. You might spread your dollars across two or three of them, or all of them. Just be sure to have a plan for how you'll amass the money you'll need by retirement, and act on that plan, whether it involves investing in ETFs over the long run or not. 10 stocks we like better than WalmartWhen our award-winning analyst team has an investing tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* They just revealed what they believe are the ten best stocks for investors to buy right now... and Walmart wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks Stock Advisor returns as of 6/15/21Suzanne Frey, an executive at Alphabet, is a member of The Motley Fool's board of directors. Teresa Kersten, an employee of LinkedIn, a Microsoft subsidiary, is a member of The Motley Fool's board of directors. Randi Zuckerberg, a former director of market development and spokeswoman for Facebook and sister to Meta Platforms CEO Mark Zuckerberg, is a member of The Motley Fool's board of directors. John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Selena Maranjian owns Activision Blizzard, Alphabet (A shares), Alphabet (C shares), Amazon, Apple, Costco Wholesale, Datadog, DocuSign, Intuitive Surgical, Meta Platforms, Inc., Microsoft, and Starbucks. The Motley Fool owns and recommends Activision Blizzard, Airbnb, Inc., Alphabet (A shares), Alphabet (C shares), Amazon, Apple, Costco Wholesale, CrowdStrike Holdings, Inc., Datadog, DocuSign, Intuitive Surgical, Meta Platforms, Inc., Microsoft, Nvidia, Palo Alto Networks, Starbucks, Tesla, Vanguard Total Stock Market ETF, and Zoom Video Communications. 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