The thinking behind the use of GPA is that past performance is a reliable predictor of future achievement. Some schools use an overall undergraduate GPA as an admission criterion. Some schools narrow the focus even further, and concern themselves primarily with the GPA in the applicant's major. One safe generalization about GPA as an admission requirement is that the minimum GPA for admission to a graduate degree program is significantly higher than the GPA required to graduate with a bachelor's degree.
Many schools require a C average to receive an undergraduate degree.
Most graduate programs require at least a B average for admission, and applicants to highly competitive graduate programs often have GPAs in the high B and A ranges. Undergraduate GPA is the most common criterion used in admission, but it is not, as mentioned above, an infallible predictor of graduate success. This is because there can be non-academic factors which affect academic performance. One such non-academic factor is the student's maturity on entering college. The undergraduate experience is qualitatively different from high school, and many people take some time to adjust to it.