In baseball statistics, hits per nine innings (denoted by H/9) is the average number of hits allowed by a pitcher in a nine inning period; calculated as: (hits allowed x 9) / innings pitched. This is a measure of a pitcher's success based on the number of all outs he records. As of February 2022, Nolan Ryan is the career leader (6.5553), Sandy Koufax is #2 (6.7916), Clayton Kershaw is #3 (6.8160).