GMAT scores are famously quoted on a scale of 200-800, following a tradition that dates to the first American psychometric tests, in the 1940s. Percentile scores, however, are quoted in positive integers - from 1st to 99th - and indicate relative performance against a large population of test-takers. For example, a 600 GMAT score is in the 56th percentile, meaning 56 percent of test-takers scored below 600.
HOW TO USE PERCENTILE SCORES
For purposes of GMAT prep, the percentile score is used to forecast, not only the overall effort you'll need to put in, but also the most efficient mix of course work, in-person tutoring, and individual study. This is not exactly a one-step procedure, but it is simple enough. First, calculate a score gap, the measure of the overall effort required to reach your target score. Then, consider the deadlines for your target programs. Together, you'll have an estimate of the time you have to invest, and the gap you need to bridge. That will decide how much third-party input you should get. The right decision here can not only improve your return on investment of time and money... it can also mean the difference between reaching your score in time, and reaching it too late.