EXHIBIT 11 AIRGAS, INC. EARNINGS PER SHARE CALCULATIONS Three Months Ended June 30, (In thousands, except per share amounts) 2000 1999 Weighted Average Shares Outstanding: Basic shares outstanding 65,100,000 69,800,000 Stock options - incremental shares 400,000 1,200,000 Contingently issuable shares 1,800,000 100,000 Diluted shares outstanding 67,300,000 71,100,000 Net earnings $9,816,000 $9,085,000 Basic earnings per share $.15 $.13 Diluted earnings per share $.15 $.13