You don’t get to know for sure what college will cost until you apply and get in. Colleges provide tools that help you guess what kind of financial aid they might offer, if any, but the numbers are often off by many thousands of dollars.

The fact that this real price is a mystery for most people at most schools is disgraceful. It also presents an opportunity.

A few weeks ago, Brandeis University quietly introduced a new tool for college shoppers called Faye. It asks questions like a person would, digests high school transcripts and tax returns, then tells you “what your Brandeis cost will be” if you get in, including both need-based and merit aid.

“Will” suggests certainty. And certainty is decidedly not what colleges offer with the net price calculators that federal law requires them to provide applicants. Those calculators are the tools that lead to sticker shock when an admission offer arrives with an actual price that is far higher than the calculators’ estimates.

I don’t know of any schools that do what Brandeis is trying. It may not work, and it may backfire in a couple of different ways. But the fact that the school is even trying it is a kind of victory for anyone who has ever wailed in agony over the complexity of college pricing and the futility of trying to figure it out.

The person who signed off on Faye (as in F.A., or financial aid) is Arthur Levine, the Brandeis president. The son of a South Bronx mailman, he was able to attend Brandeis himself in the late 1960s only because a well-off relative helped.

Dr. Levine did not come up with Faye. He has long been pals with John Katzman, whose name will be familiar to Gen X-ers who took his Princeton Review SAT classes. Mr. Katzman’s punk-rock approach to test preparation over the years, which included trying to trade his archrival’s internet address for a case of beer, made him a folk hero to students and an irritant to people in power.

I first met Mr. Katzman in the 1990s when Random House republished, under its Princeton Review imprint, an out-of-print book about gap years that I had co-written. But we hadn’t spoken in about 25 years until he emailed about Brandeis. He’s no longer affiliated with Princeton Review and started a higher-education company called Noodle in 2013.

He shopped the upfront pricing idea around for a while before trying it on Dr. Levine. But it was slow to gain traction because real pricing, pre-application, is just not how things are done in the residential undergraduate education industry.

To get any kind of a binding price under the current system, you generally must apply and get in. Then, perhaps you appeal for a better offer, if the school can digest your appeal in time. This year, Northeastern could not for some students.

And then, more! Maybe a different college surprises you with an even better offer — even after the May 1 decision deadline.

To call it a goat rodeo is to engage in a kind of goatism.

Brandeis’s enrollment team was well aware of this mess. But its members weren’t sure there was any overarching fix, given regulatory and other constraints, and they greeted Mr. Katzman with arched eyebrows.

“We thought he was nuts,” said Sherri Avery, assistant vice president of student financial services at Brandeis.

“If it could be done, someone would have been doing it, right?” said her boss, Jennifer Walker, vice president for enrollment management.

“And we wanted to do it,” Ms. Avery added.

Mr. Katzman’s premise was simple. Most need-based and merit aid calculations are formulaic and algorithmic, even if they differ at least a bit from one another. Ever-evolving technology ought to be able to handle it.

Faye is simple to use, and the price quotes it produced in my tests were easy to understand. What gave me pause was that the word “guarantee” did not appear anywhere near the dollar figure. One recent test triggered an email that was supposed to confirm Faye’s “will pay” price, but it referred to the number as a “projection.”

In my first meeting with the Noodle team, the G word came up repeatedly. Since then, however, the Brandeis and Noodle wordsmiths struggled mightily before they settled on the “will pay” language.

Why no guarantee? Blame the lawyers, who demanded asterisks that the team thought would be off-putting.

Indeed, there will be situations — estranged parents who won’t submit tax returns, small-business owners in various circumstances — that will require human intervention. A “will pay” offer could still come, but from humans, later, and not from Faye right away.

Then, there’s Faye’s garbage-in, garbage-out rule: If you make an error, it’s on you. If you lie, Brandeis won’t honor the quote. And if the software messes up, Brandeis reserves the right to re-price your deal.

There’s more. If your child is a high school sophomore or younger, the “will” does not apply, since your finances may change and Brandeis’s list price will for sure.

Brandeis may also change its merit aid formula if the school becomes more popular. It received 40 percent more applications this year, which may give the school enough marketplace power to offer fewer merit aid discounts. (Merit aid for current students doesn’t change from year to year as long as they keep their grades up and finish within eight semesters.)

And finally, if your household income or assets change drastically during your time at the school, your net price might, too, if you receive need-based financial aid.

So much throat clearing. So many maybes. All these asterisks make the whole endeavor seem asterisky, and it is.

If you’re a school, any big change in how you sell can alter who will matriculate and what they can and will pay. If net tuition revenue per student then plummets, you have an enormous problem. Competitors will scrutinize Brandeis’s tool, and some of them may undercut its prices.

And if enough people use the tool but can’t get sensible offers, the university loses them before they even apply. Application numbers could fall as quickly as they rose.

“That’s hard,” Mr. Katzman said. “But it’s the same hard as every airline and hotel and everyone in the real world has to deal with. I have to set a price, and I have to tell people what it costs.”

That’s the other reason there is no “guarantee.” College-pricing nerds like me think the word is a solution to what ails higher education. But in Faye’s testing, the word generated more questions than excitement among parents and students, and there was a risk that it might sound gimmicky.

So if you are a college shopper, test Faye mercilessly. If your finances seem broken, try to break Brandeis with your complex situation.

And save that “will pay” price quote. If you apply to Brandeis and get in, send me a note and let me know if the price changed.

But before then, ask this when you talk to other colleges: Why won’t you tell me what you will charge, pre-application? Heck, do it in the group information session in front of 100 other people. Maybe the school will surprise you.

Some institutions will make this work eventually, even if it isn’t Brandeis. And hats off to Cornell College, Whitman College and the College of Wooster, which have their own transparency initiatives.

Ms. Avery and Ms. Walker no longer think Mr. Katzman is crazy. And over lunch in March, they talked about the risk that their price quotes could scare people away.