Your Student Aid Index-- the amount that the FAFSA says your family can pay for college-- gets a lot of air time. But there's another number that's more important: Net Cost. Your Net Cost is your actual cost to attend a college. Net cost matters because colleges are under no obligation to meet your financial need. That means that just having a low SAI doesn't guarantee financial aid-- you have to find colleges that will meet your financial need through grants and scholarships.

Here's the deal: colleges have two kinds of prices, list price and net price. The list price is the total cost of tuition, fees, room and board, books and other expenses. Most students don't pay list price, though: they get financial and aid scholarships that reduce the cost of attendance. The net price is how much you pay net of financial aid and scholarships. And that's a much more important number than either your SAI or the list price.

How do you find your net price? Every college is required to have a net price calculator on its website. You enter your data into the net price calculator and it will show you what students like you currently pay to attend the college. The estimate you get from the net price calculator isn't binding on the college, but it will give you a pretty good idea of what types of aid you'll be eligible for at that school.

Doing a few different net price calculators will help you to see all the different ways colleges package financial aid and the range of prices you are likely to find in offer letters. They can also be helpful in narrowing down your list of colleges to which you'll apply. When my daughter was looking at colleges, we got estimates ranging from $11,000 to $81,000 per year, which helped us to eliminate a number of colleges. And all of her acceptances came with aid packages that were within $2,000 of what the net price calculators had told us to expect.

Net price calculators have limits. They're less good for families with highly variable income. And they might not include merit scholarships. If the net price calculator doesn't ask about academics, that could mean one of two things: either the college doesn't offer merit scholarships, or you need to visit the scholarship page of their website to find out about merit scholarships, eligibility and application process.

That's not to say that your Student Aid Index doesn't matter. SAI is helpful for determining whether you're a candidate for need-based aid in the first place. If your SAI is higher than the list price of a college, you won't be getting any need-based aid. That means you should look for colleges that will offer you merit scholarships if you don't want to pay full price. SAI also determines whether you're eligible for federal financial aid programs including a Pell Grant, a subsidized loan or work-study at your college, as well as many state-based grants.

Just remember that a low Student Aid Index is not a guarantee of scholarships at the college of your choice. That depends on the college's financial aid policies and how they package awards, and net price calculators are a great place to learn more about that.

Are you a high school or middle school teacher or counselor? If you'd like a free copy of my book How to Pay for College for your school, leave me a note in the comments here!