자기 나이에 얼마를 저축해야 하는가? Here's how much money you should have saved at every age.

When it comes to savings, Americans are falling short.

 Nearly 70% of adults have less than $1,000 in their savings accounts .

Retirement funds are looking equally bleak.

 In fact, about half of US families have zero retirement account savings .

"Particularly the younger generation likes to think, 'I'll save more when I'm making more.'

But whether you're making $50,000 a year or $200,000 a year, we all have challenges saving," says Kimmie Greene, money expert at Intuit and spokeswoman for Mint.com.

"Because oftentimes what happens is, when people make more," she says, "they end up spending more." The sooner you start saving — for retirement or any other major purchases you hope will be in your future — the better.

After all, time is on your side when you're young, thanks to the power of compound interest. While the amount you need in savings is highly personal, and specific dollar amounts can be arbitrary, Greene offers a simple formula to help you figure out if you're setting aside enough money.

In your 20s: Aim to save 25% of your overall gross pay, Greene tells CNBC.

"That 25% is the combination of 401(k) withholdings, matching funds from your employer and any cash savings that you have," she notes. "It can also include debt repayment.

"Just make sure your lifestyle expenses don't exceed 75% of your gross income."

 By age 30: Have the equivalent of your annual salary saved, Greene says.

 If you earn $50,000 a year, aim to have $50,000 in savings when you hit 30.

Again, this includes any retirement account contributions, matching funds from your company, cash savings, or money you have invested elsewhere, in index funds or robo-advisers.

By age 35: Have twice your annual salary saved.

 By age 40: Have three times your annual salary saved.

By age 45: Have four times your annual salary saved.

By age 50: Have five times your annual salary saved.

 By age 55: Have six times your annual salary saved.

By age 60: Have seven times your annual salary saved.

By age 65: Have eight times your annual salary saved.

Greene's timeline is similar to the one recommended by retirement-plan provider Fidelity Investments, which says a good rule of thumb is to have the equivalent of your salary saved by age 30 and to have 10 times your final salary in savings if you want to retire by age 67.

 "While this can sound super daunting today, if you're putting that money to work starting in your 20s, it's not as difficult as it sounds," says Greene.

She also notes that "life is anything but linear," and it's impossible to follow this formula to a tee.

You may have to adjust accordingly and save more or less in any given year, depending on major life events, such as having a kid or buying a home.

Need help spending less and saving more?

Check out: 8 strategies for saving money from a couple that banked $50,000 last year After living on $60 a week for a month, here are my 7 best money-saving tips 11 useless things to stop wasting your money on in 2017