Imagine having to make a decision about a house or car purchase without knowing exactly what it costs.

The admissions staff at College of William and Mary would tell you their tuition rate for 2012-13 if they knew it. But they don’t. ( Associated Press)

Many of the nation’s most popular public universities don’t set tuition until April or May, or even June or July, because they don’t know how much money they will be receiving from their states. Students who troll for tuition data on the admission page will find data for the current academic year, but not for next year. That group includes the University of Maryland, the College of William and Mary, Penn State, the University of North Carolina, the University of Michigan, Indiana University and the University of the District of Columbia.

Towson University and the University of Virginia gamely offer up estimates of next year’s expenses, although their tuition, too, remains to be set.

“Tuition won’t be set until the April board meeting, because until that time there’s no state budget in place,” said Henry Broaddus, dean of admission at William and Mary.

That means the college has to work out “preliminary” aid packages for students who qualify for financial assistance, based on this year’s costs, and then adjust the award as needed after trustees set tuition.

“Although the situation certainly is not ideal, the reality is that universities face the same uncertainty with respect to state funding that families face with respect to tuition costs,” Broaddus said.

Private universities face no such impediment; they are free to set tuition when they wish, and many have posted rates for next fall, including George Washington University, Georgetown, Penn, the University of Richmond, Catholic University, St. John’s College and Goucher College.

(Finding the pages, however, can be tricky, at least by comparison to the plainspoken publics. Pick one of the schools listed above, enter the site through Google and see how many clicks, and how much time, it takes you to find the latest tuition numbers. It took me more than a dozen clicks on some sites, and I am supposed to be good at this.)

Others have not yet revealed next year’s rates. I could find no 2012-13 tuition for American University, Hampden-Sydney College, Lynchburg College or Tulane. Other schools make the numbers rather hard to find. Washington College, for example, mentions its 2012-13 costs in the middle of a lengthy passage on financial aid, rather than on its own dedicated page.

Then again, for private universities, guessing at next year’s tuition rate isn’t all that hard. Published prices are rising 4 to 5 percent a year, according to the latest College Board report.

Estimating tuition increases in the public sector can be considerably more treacherous. Virginia Commonwealth University raised tuition 24 percent in 2010. The average California public university raised expenses 21 percent last year. And no one knows what those schools will charge in fall.