Editor's note: Calculations in this story have been revised by using a more accurate tool.
Young people are pretty confident about their financial futures. A recent survey from TD Ameritrade found that 53 percent of millennials expect to become millionaires at some point in their lives, if they aren't already.
While 23 percent believe they'll hit $1 million by age 50 or older, many expect to get there more quickly. A full 19 percent say they'll become a millionaire by age 40 and 7 percent predict it'll happen by 30.
But what if you want to speed up the process and reach that milestone in the next 15 years? It could be possible, if you're willing to work for it — and put away much more each month than the average American.
Using Bankrate's millionaire calculator, CNBC Make It found how much you'd have to save each month to become a millionaire by 2033. Here's how much you'll need to put away, depending on the amount you already have invested.
With a 4 percent rate of return: $4,075 per month
With a 6 percent rate of return: $3,500 per month
With an 8 percent rate of return: $2,945 per month
With a 4 percent rate of return: $4,000 per month
With a 6 percent rate of return: $3,375 per month
With an 8 percent rate of return: $2,850 per month
With a 4 percent rate of return: $3,930 per month
With a 6 percent rate of return: $3,325 per month
With an 8 percent rate of return: $2,775 per month
The average annualized total return for the S&P 500 index is more than 9 percent. But it's important to keep in mind that these calculations don't account for the many variables that can affect wealth over several decades, including windfalls, emergencies and rises or dips in the market.
Of course, saving hundreds or thousands a month is an ambitious goal. Even $1,000 a month is more than most Americans can manage. But getting into the habit of saving any amount will be great for you in the long run.
Here are a few simple, low-stress ways to start investing:
Correction: This story has been revised to use a more accurate calculator tool.
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