EXHIBIT 11 AIRGAS, INC. EARNINGS PER SHARE CALCULATIONS Three Months Ended June 30, 1999 1998 Weighted Average Shares Outstanding: Basic shares outstanding 69,800,000 70,300,000 Stock options - incremental shares 1,200,000 1,800,000 Contingently issuable shares 100,000 -- Diluted shares outstanding 71,100,000 72,100,000 Net earnings $9,085,000 $11,275,000 Basic earnings per share $ .13 $ .16 Diluted earnings per share $ .13 $ .16