It's not a secret that saving independently is an essential step toward attaining financial security during retirement. But new data reveals that the youngest generation of workers may be underestimating the amount of retirement savings they need.

In a recent BlackRock report, 36% of Gen Zers say they'd need a savings balance of under $250,000 for a comfortable retirement. By contrast, nearly 50% of baby boomers point to a $1 million to $3 million nest egg as the amount needed to maintain a comfortable standard of living once their careers wrap up.

If you're in the $250,000 or under camp, you may be setting yourself up for a world of financial stress in retirement. And the sooner you realize that, the sooner you can make adjustments to your financial plans.

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Why a nest egg of $250,000 or less won't cut it

The money you bring with you into retirement is money that potentially needs to last for decades. And so you'll need to be careful not to withdraw too much money from your IRA or 401(k) plan at once.

For years, financial experts have advocated a 4% annual withdrawal rate. In recent times, that rate has been questioned. But even if we use it as a starting point, for a $250,000 nest egg, a 4% withdrawal amounts to $10,000 of annual retirement income. That's certainly not a lot of money.

Of course, there's also Social Security. The average recipient today collects $1,661 a month, which translates into roughly $20,000 a year.

But Social Security benefits may be subject to universal cuts if lawmakers don't find a way to pump more money into the program. And while today's younger workers should expect something from Social Security, it's hard to determine exactly what future benefits will look like.

Even if we're optimistic and assume that lawmakers manage to avoid benefit cuts, $20,000 in Social Security income plus $10,000 in nest egg withdrawals does not make for a very generous annual retirement salary. And so younger workers would be wise to aim higher in terms of their savings -- and start socking more money away at a young age.

The good news is that Gen Zers have time on their side. Saving $400 a month over 40 years and investing that money at an average annual 8% return (which is a bit below the stock market's average) results in a nest egg worth $1.24 million.

When we apply a 4% withdrawal rate to that sum, we get nearly $50,000 in annual income -- a vast improvement over $10,000. That's a more reasonable sum of money to live on -- and it doesn't even account for Social Security.

Of course, today's younger workers may also have a different vision of retirement -- one that involves continuing to work in some capacity to keep generating income. For those looking to go that route, a savings balance of $250,000 or less may suffice. But the more savings you're able to bring into retirement, the better, so even if working as a senior is part of your plan, it still pays to ramp up your IRA or 401(k) contributions while you can.