The amount of money Americans think they'll need to spend their post-work years in comfort keeps rising.

On average, Americans say they'll need around $1.46 million to retire comfortably, according to Northwestern Mutual's 2024 Planning and Progress study. That represents a 15% increase from last year's $1.27 million and a 53% increase from their $951,000 goal in 2020, per the report.

And younger generations think they'll need even more.

Gen Z, defined as people between the ages of 18 and 27, say they'll need around $1.63 million, according to the study. Millennials, defined as those 28 to 43, expect they'll need $1.65 million.

"People's 'magic number' to retire comfortably has exploded to an all-time high, and the gap between their goals and progress has never been wider," Aditi Javeri Gokhale, Northwestern Mutual's chief strategy officer and head of institutional investments, said in the report. "Inflation is expanding our expectations for retirement savings, and putting the pressure on to plan and stay disciplined."

With that in mind, CNBC calculated how much someone who earns $50,000 annually should set aside each month in order to retire with $1.46 million at age 65. These calculations assume you begin saving with $0 and don't account for unpredictable life events such as raises, promotions, layoffs or market volatility.

If you start at 21

• Earning a 5% annual rate of return: $759 per month
• Earning a 7% annual rate of return: $414 per month
• Earning a 9% annual rate of return: $216 per month

If you start at 25

• Earning a 5% annual rate of return: $957 per month
• Earning a 7% annual rate of return: $556 per month
• Earning a 9% annual rate of return: $312 per month

If you start at 30

• Earning a 5% annual rate of return: $1,285 per month
• Earning a 7% annual rate of return: $811 per month
• Earning a 9% annual rate of return: $496 per month

Although having a savings goal in mind can be helpful when planning for retirement, it can also feel a bit overwhelming if you're a long way off from reaching that number. Plus, your retirement account balance can be impacted by factors outside of your control like volatility in the stock market.

That's why it's important to focus on the things within your control, such as your savings rate. That's the percentage of your annual income you set aside for retirement each year.

Fidelity Investments, one of the country's largest 401(k) providers, recommends a savings rate of 15%, inclusive of your employer's match if available.

Even if you can't set aside much for retirement now, it's better to start sooner than later, says Anne Lester, a retirement expert and author of "Your Best Financial Life: Save Smart Now for the Future You Want."

"The best thing to do is start when you're young," she tells CNBC Make It. "It's a really powerful thing to do because the money you save will have more time to grow for a longer amount of time."

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