The unsavvy consumer may not understand the importance of checking one credit rating, let alone three. The FICO score, invented many years ago by the Fair Isaac Corporation, can range from 300 to 850, with a higher score being more ideal. It is directly used by lenders to determine your credit risk, i.e. whether or not they should loan you money.

Relatively simple, right? Well, not really. Inexplicably, three major credit bureaus keep track of Americans’ credit history and use different formulas and information to calculate a FICO score. These companies are TransUnion, Equifax and Experian. Lenders can pull one or all three of your credit scores. They will often pull all three and use the middle score, or use the average of all three.

According to Business Week:

“For the most detailed explanations on your FICO scores, go to myfico.com. A score from one credit bureau costs $14.95, all three are $44.85. It’s useful to buy all three because large lenders either average the scores or take the middle one. You’ll want to check your FICO scores once a year or several months before you apply for a loan.”

The point differential between your three credit scores could be as much as 50 points, because different bureaus track different information at different times, directly affecting the score they give you. So be your own most thorough investigator and give yourself the advantage when going in for a loan.