According to the latest inspection report by Estyn, the school is rated as Excellent and, 'the standards achieved by pupils are consistently very high and well above expectations.' Cardiff High School is a Green Category school and in Standards Group 1. It was also ranked Number 1 in the most recent Real Schools Guide. In 2016, GCSE and A level results were record breaking for the school and placed Cardiff High School as the top achieving school in both the city and across all of Wales for the third year running based on the number of pupils achieving 5 A*-C grades including Mathematics and English.