College graduations are a time for inspirational words and optimism about the future. But the post-college world can also bring sobering realities.

Educational services company Cengage surveyed 2,500 recent and upcoming graduates for the Cengage Student Opportunity Index and found that respondents, on average, believe it will take six years to pay off their student loans.

In reality, it will take closer to 20.

Cengage found that 51% of the recent and soon-to-be college graduates surveyed have student loan debt, with an average reported total of $22,919 in student loans upon graduation. And some estimate these totals may be even higher. According to Student Loan Hero, 69% of students from the Class of 2018 took out student loans, graduating with an average debt balance of $29,800. And according to the College Board, the average cumulative student debt balance in 2017 was $26,900 for graduates of public four-year schools and $32,600 for graduates of private nonprofit four-year schools.

The Department of Education reports that the typical repayment period for borrowers with between $20,000 and $40,000 in federal student loans is 20 years, and a 2013 study of 61,000 respondents conducted by One Wisconsin Institute found that the average length of repayment for student debt borrowers is 21.1 years.