Americans continue to find ways to make money outside of their primary sources of income. More than a third, 36% of U.S. adults have a side hustle, according to a new Bankrate survey of 2,332 people. And they're making a sizable chunk of extra change.

The average side hustler is bringing in $891 per month. That's up from $810 per month in 2023, or a 10% increase altogether, says Ted Rossman, senior industry analyst at Bankrate. The practice is now "quite a bit more lucrative."

There are some differences among generations and not everyone is bringing in hundreds of dollars per month. Here's a breakdown of how much people are making and some of the most in-demand side hustles people are taking on.

Millennials are bringing in $1,129 per month, on average

Gen Zers are the most likely to tack on a side hustle, with 48% reporting they have one. That's followed by 44% of millennials, 33% of Gen Xers and 23% of Baby Boomers.

But Millennials are still seeing the most extra cash. On average, they bring in $1,129 per month. That's followed by Gen Zers, who are bringing in $958 per month, Gen Xers, who are bringing in $751 per month, and Baby Boomers, who are bringing in $561.

Overall, 28% of people make more than $500 per month, 34% make between $101 and $500 and 37% make $100 or less. Median earnings are $250, versus $200 per month in last year's study. It's a small monthly hike, but high earning hustlers are still skewing the average much higher.

Popular gigs: furniture assembly, data analysis, pet sitting

So, what are people doing to earn their extra money? It's likely all sorts of things.

In 2024, the most in-demand gig on services platform Taskrabbit is furniture assembly, which pays an average of $41 per hour, according to the site. One of freelance marketplace Upwork's most in-demand skills is data analytics, which can pay $167 per hour.

"I think dog walking or dog sitting or pet sitting is such a popular one because you really don't need anything except a little credibility," says Jen Glantz, founder of Bridesmaid for Hire and the creator of the Monday Pick-Me-Up and Odd Jobs newsletter. Nationwide, the average pay for pet sitters is $16 per hour, according to ZipRecruiter.

"Another popular one I've seen is something like a Poshmark," she says, "where you list your stuff and sell it." Sellers like Maria Jones, Kaitlin Kao and Sophie Riegel have made thousands using the site.

Ultimately, founder and CEO of Sidehusl.com Kathy Kristof attributes side hustlers' success to their broader understanding of what's on the market. They're being selective in the side hustles they take on to make sure they're actually bringing in money.

"You saw a lot of people getting taken advantage of in the gig economy and I think they're just a little bit less gullible now," she says.

Want to stop worrying about money? Sign up for CNBC's new online course Achieve Financial Wellness: Be Happier, Wealthier & More Financially Secure. We'll teach you the psychology of money, how to manage stress and create healthy habits, and simple ways to boost your savings, get out of debt and invest for the future. Start today and use code EARLYBIRD for an introductory discount of 30% off through September 2, 2024.

Plus, sign up for CNBC Make It's newsletter to get tips and tricks for success at work, with money and in life.