Unexpected surprises for families of college students between a college's advertised "sticker price" and the actual costs prompted Congress in 2011 to require schools to offer net-cost calculators. While these tools can help families to plan accordingly, college officials advise parents to take them with a grain of salt. "They can tell you whether a college is inside or outside the ball park of affordability. But they can't tell the difference between home plate and center field. I wouldn't rule out a college based on net price," said financial aid expert Mark Kantrowitz.