EXHIBIT 11 AIRGAS, INC. EARNINGS PER SHARE CALCULATIONS Three Months Ended June 30, 1998 1997 Weighted Average Shares Outstanding: Basic shares outstanding 70,300,000 66,800,000 Net common stock equivalents 1,800,000 2,400,000 Diluted shares outstanding 72,100,000 69,200,000 Net earnings $11,275,000 $12,226,000 Basic earnings per share $ .16 $ .18 Diluted earnings per share $ .16 $ .18