Overall, the average amount millennials say they need to be happy has risen $30,000 since 2016, jumping from $50,000 a year to $80,000.

It's also significantly more than their female counterparts, who report needing only a minimum income of $58,500 per year to be happy. In 2016, millennial women said they needed an average of $48,500.

That's more than double the salary they reported needing only two years ago, when they said they'd be content with a comparatively modest $55,000.

In order to be happy, millennial men, defined here as those aged 21 to 37, say they need to earn an average of at least $118,000 per year, according TD Ameritrade's recent "Millennials and Work" survey.

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Nearly a quarter of millennials (22 percent) say they need to earn between $50,000 and $74,999 a year to be happy, while 41 percent say they need $75,000 or more. That's significantly more than young people actually take home: Those between the ages of 25 and 34 earn a median salary of just $41,288 per year, according to BLS, and SmartAsset estimates that those 19 to 37 years old earn an average of $35,592.

It's worth noting that the survey didn't ask how millennials spend their money. Spending plays a key role in how money relates to happiness. Studies have shown that money can increase happiness when it's used to save time, create lasting memories or be generous to others.

Achieving a certain level of wealth can also give individuals the freedom to start their own businesses or to retire early.

And although young people, and men in particular, seem to have high expectations, many of them are also putting in the required effort. Over 40 percent of survey respondents have a side hustle, for example. Technology has made it easier than ever to get started making extra money on the side, like by driving for ride-sharing apps or renting out spare rooms.

Chris Bohlsen, a director in investor services at TD Ameritrade, believes the average amount millennials say they need to be happy will rise even more as the generation ages: "They will continue to have higher goals because they're putting in the work to achieve the goals that they have right now," he tells CNBC Make It.

Don't miss: Here's how much money millennials say they need to make to be happy

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