The average GPA at Mercer University is 3.71. (Most schools use a weighted GPA out of 4.0, though some report an unweighted GPA. With a GPA of 3.71, Mercer University requires you to be above average in your high school class.You'll need at least a mix of A's and B's, with more A's than B's.he average SAT score composite at Mercer University is a 1730. This score makes Mercer University Competitive for SAT test scores. The 25th percentile SAT score is 1590, and the 75th percentile SAT score is 1890.