A whopping 233,000 Americans have stashed at least $1 million in their 401(k) accounts, according to a survey from Fidelity Investments. Entry into this exclusive club may seem out of reach for many investors, but retiring a millionaire is more achievable than you might think.

The 401(k) is one of the most powerful investment tools out there, so if you're fortunate enough to have access to one, it's wise to take full advantage of it. And there are three things in particular you should be doing to ensure you're able to save as much as possible.

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1. Contribute enough to earn the full employer match

Employer matching contributions are essentially free money, so if you're not contributing enough to your 401(k) to receive the full match, that's cash left on the table. If you're consistently missing out on that free money year after year, it can potentially add up to tens of thousands of dollars in lost savings.

Say, for instance, you're 40 years old with $50,000 in savings. Let's also say you're earning a salary of $50,000 per year, and your employer will match your 401(k) contributions up to 3% of your salary, or $1,500 per year. Assuming you're earning a 7% annual rate of return on your investments, here's approximately how much you'd have saved over time if you'd contributed $1,500 per year and earned the full match, versus if you'd only saved $1,000 per year and earned a $1,000 match.

Age Total Savings When Contributing $1,500 Per Year (Plus $1,500 Match) Total Savings When Contributing $1,000 Per Year (Plus $1,000 Match)
40 $50,000 $50,000
45 $87,000 $82,000
50 $140,000 $126,000
55 $213,000 $188,000
60 $316,000 $276,000
65 $461,000 $398,000

Source: Author's calculations

In other words, in this scenario, saving just $500 more per year and collecting the full match can result in an additional $63,000 in savings by retirement age.

2. Take advantage of catch-up contributions

As of 2020, you're allowed to contribute up to $19,500 per year to your 401(k). However, if you're age 50 or older, you can save an additional $6,500 per year, bringing your contribution limit up to $26,000 per year.

If you're determined to save as much as possible in your 401(k), it's wise to take advantage of these catch-up contributions. Maxing out your 401(k) is tough and may not be feasible for everyone, but if you're able to supercharge your savings, that extra $6,500 per year can go a long way when you're in the final stretch of your career before retirement.

3. Consider adjusting your asset allocation

Asset allocation refers to how your investments are divided within your portfolio. Younger investors will typically invest more aggressively, allocating more cash toward riskier investments like stocks. Then, as you get older, your portfolio should begin to shift to more conservative investments like bonds.

Investing appropriately for your age can help maximize your savings. If you're investing too aggressively when you're only a few years from retirement, a stock market downturn could significantly hurt your investments just before you retire. On the other hand, if you still have decades before you retire and you're investing too conservatively, your savings won't grow as much as they could if you'd invested more aggressively.

A general rule of thumb is to subtract your age from 110, and allocate the result as a percentage of your portfolio toward stocks. So, for instance, if you're 50 years old, you should be investing 60% of your portfolio in stocks and 40% in bonds. Keep in mind that this is just a guideline, though, so your asset allocation could differ based on your tolerance for risk.

Retiring rich may be a lofty goal, but with a strategy in place, it may be well within reach. By maximizing your savings and investing in the appropriate places, you'll be on your way to joining the 401(k) millionaires club.