How much money do Americans in their 20s have in their 401 (k) s?

Millennials tend not to know how they manage their money. But how much do young people really save for their future?

CNBC Make It turned to Fidelity, the largest pension provider in the country, for the numbers.

For those 20 years and over with 401 (k) plans, the average balance in Q1 2019 is $ 11,800. Fidelity also found that this group contributed 7% of their paychecks and that their employers averaged 4%, which places their total savings rate at 11%.

The data was provided to CNBC Make It by Fidelity, the largest pension provider in the country.

Here are the average age contribution rates, also from Fidelity. These rates do not include corresponding employer contributions.

Do not forget that Fidelity's data only takes into account Americans with a retirement account, so they do not give a complete picture. Nearly a quarter of American adults have no savings for retirement and young workers aged 18 to 29 are less likely to do so, with 42% saying they have not hidden anything.

The answer to this question is very personal and depends on your lifestyle, your expenses and your consumption habits, but there are some basic rules to follow if you want to take a comfortable retirement.

Some experts, including AE Wealth Management co-founder David Bach, say that if you set aside at least 10% of your income, everything will be fine. Plus, it's always better: Bach says that if you want to retire "rich", save 15 to 20% and, if you want to retire earlier, save 20% or more.

Fidelity recommends saving 15%. This amount includes personal contributions as well as the corresponding contributions from your company.

If you can not save 15% right away, "be sure to save at least enough for your employer to fully match," Taylor said. Then, "commit to increasing your contribution by 1% to 2% each year until you get there," she says, adding, "Starting early, whatever the amount, is always a great idea . "

Time is on your side when you are young. The sooner you start putting your money to work, the less you will need to save each month to achieve your goals, thanks to the power of compound interest.

If you start at age 23, for example, you only need to save about $ 14 a day to become a millionaire at age 67. This badumes an average annual investment return of 6%. If you start at age 35, however, you will need to reserve $ 30 a day to reach seven-digit status at age 67.

No matter how far you are from retirement, do not wait to start saving.