Admission to Stanford University is highly competitive. While the school does not stipulate a formal minimum for standardized test scores, virtually all accepted applicants submit very high scores. In 2012, fewer than 25 percent of accepted applicants posted ACT scores lower than 31. That means that 75 percent of Stanford freshmen scored in the 97th percentile or better on the exam. It's possible to get in with a lower score, but it's very unlikely.
Converting SAT and ACT Scores
Stanford, like many colleges and universities, accepts both SAT and ACT scores for consideration in the admissions process. According to the ACT organization's website, a composite ACT score of 31 equates to a combined score of 1380 on the SAT's critical reading and math tests. A combined score of 31 on the ACT's English and writing tests equates to a score of 690 on the SAT's writing test. Stanford doesn't have a minimum required score for the SAT, either, but in 2012, 75 percent of Standford freshman posting SAT scores scored higher than a 680 on the Critical Reading section of the test, and higher than a 700 on both the Math and the Writing portion of the exam.