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Without a universal version or a clear way to differentiate what aid and data are and are not included in each calculation, families should be wary of sweeping comparisons, Kantrowitz says—a problem that's long been cited with comparing differing financial aid letters.
Users, he adds, should also take the estimates for what they likely are: ballpark figures.
"The calculators are probably going to have thousands of dollars difference between their estimates and what the actual figures turn out to be," Kantrowitz says. "They're useful tools for ruling in a school that you might have considered, but they're not useful tools for comparing colleges or for excluding a college.
"If there's a college you want to consider, and its net price is shown to be much higher than the other colleges that you're considering, don't necessarily rule it out."
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Despite some early kinks in the calculators, many school officials say the mandate is a positive step in the evolution of college cost transparency.
"Parents always feel so guilty that they couldn't save enough, [but] there's no way they could have saved enough to have kept up with the price of college," Rice's Walker says. "If we can get families out there looking at these calculators, at least they're going to start getting a better idea of what the costs are going to be so they can start managing those expectations with their son or daughter."
The estimations have helped Robyn Sekula, who is already anxious about covering the future college costs of her three daughters under the age of 9. Consulting a net price calculator several years ago showed that she would ultimately need about $420,000 to cover three educations—a staggering but motivating sum, she says.
"I really felt overwhelmed when I saw those numbers, but it also made me more determined to start sooner and to save up as much as I possibly could," says Sekula, a freelance writer and social media consultant who lives in New Albany, Ind. With the federal mandate in place, Sekula says, she'll check back in often to make sure she's still on track to fund her children's educations.
It's a path that Rice's Walker recommends to families with college on their radar: Consult the calculators of schools you're interested in early, and yearly. That way, prospective families hopefully won't be blindsided when the college bills begin to come in—as some current and former students may have been.
"If you talk to people in their mid-to-later 20s, if they don't have some story about the cost of college, they have a close friend who does," SAS's Whorley says. "When you really dig into that story, it's just: 'I didn't understand what it costs.' This is a big step forward."
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Clarified 10/27/11: Yale University is a client of Student Aid Services, which was not previously stated.