Here's how much money Americans in their 30s have in their 401(k)s

By the time you're in your 30s, you're nearing your peak earning years and you want to make sure you're putting your money to work effectively. One way to do that is by contributing to your 401(k) plan if your company offers one.

To give you an idea of how your retirement savings stack up against your peers, retirement-plan provider Fidelity provided CNBC Make It with the average 401(k) balances in Fidelity accounts at every age, as of the first quarter of 2019.

For 30-somethings with 401(k) plans, the average balance as of Q1 2019 stood at $42,400. Fidelity also found that this group contributes 7.8% of their paychecks and their employers match, on average, 4.6%, which puts their total savings rate at 12.4%.

Here are the average contribution rates by age, also from Fidelity. These rates do not include any matching contributions from employers.

Keep in mind that Fidelity's data only takes into account those Americans with retirement accounts so it doesn't present the full picture. Almost a quarter of U.S. adults have no retirement savings and just 36% of non-retired adults believe their retirement saving is on track.

The answer to this is highly personal and depends on your lifestyle, expenses and spending habits, but there are a few basic guidelines to follow if you want to retire comfortably.

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

Fidelity recommends saving 15%, and that amount includes contributions from your paycheck as well as any contributions from your company.

If you can't save 15% right away, "make sure that you're saving at least enough to get the full match that your employer offers," Katie Taylor, vice president of thought leadership at Fidelity Investments, tells CNBC Make It. Then, "make a commitment to yourself that you're going to increase your contribution by 1-2% every year until you get there," she says, adding: "Getting started early at any amount is always a great idea."

Ultimately, everyone's scenario is different. If you're getting a later start on saving, you may have to save more to catch up. In a 2018 report, the Stanford Center on Longevity determined that if you want to retire by age 65, you should be setting aside 10-17% of your income if you start saving as early as age 25. But if you wait until 35 to start, you have to save 15-20%.

To help you figure out the right amount to fund your retirement, try using a retirement calculator.

If you're one of the many Americans without access to a 401(k), don't stress. Most importantly, "don't let that be a deterrent for not saving for the future," says Taylor. "Whether or not you have access to a 401(k), at some point, you will want to retire and you will need to have money saved."

You have plenty of other options, including a traditional, Roth or SEP IRA; a health savings account (HSA) or a normal investment account.

Read up on all of your options, choose an account to fund and start setting aside money for your future today.

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