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EXHIBIT 11
 Airgas, Inc.
Earnings Per Share Computations
  Years Ended March 31,Basic Earnings per Share Computation
    
    2006
    
    2005
    
    2004Numerator:Income from continuing operations
    
    $
    127,515
    
    
    $
    91,558
    
    
    $
    80,649Income (loss) from discontinued operations
    
    
    (1,424
    )
    
    
    464
    
    
    
    (457
    )Cumulative effect of a change in accounting principle
    
    
    (2,540
    )
    
    
    
    
    
    
    Net earnings
    
    $
    123,551
    
    
    $
    92,022
    
    
    $
    80,192Denominator:Basic shares outstanding
    
    
    76,624
    
    
    
    74,911
    
    
    
    72,761Basic earnings per share from continuing operations
    
    $
    1.66
    
    
    $
    1.22
    
    
    $
    1.11Basic earnings (loss) per share from discontinued operations
    
    
    (0.02
    )
    
    
    0.01
    
    
    
    (0.01
    )Cumulative effect per share of a change in accounting principle
    
    
    (0.03
    )
    
    
    
    
    
    
    Basic net earnings per share
    
    $
    1.61
    
    
    $
    1.23
    
    
    $
    1.10
 Years Ended March 31,Diluted Earnings per Share Computation
    
    2006
    
    2005 (4)
    
    2004 (4)Numerator:Income from continuing operations
    
    $
    127,515
    
    
    $
    91,558
    
    
    $
    80,649Plus: Preferred stock dividends (1) (2)
    
    
    2,845
    
    
    
    
    
    
    
    Plus: Income taxes on earnings of National Welders (3)
    
    
    730
    
    
    
    
    
    
    
    Income from continuing operations assuming preferred
stock conversion
    
    $
    131,090
    
    
    $
    91,558
    
    
    $
    80,649Income (loss) from discontinued operations
    
    
    (1,424
    )
    
    
    464
    
    
    
    (457
    )Cumulative effect of a change in accounting principle
    
    
    (2,540
    )
    
    
    
    
    
    
    Net earnings assuming preferred stock conversion
    
    $
    127,126
    
    
    $
    92,022
    
    
    $
    80,192Denominator:Basic shares outstanding
    
    
    76,624
    
    
    
    74,911
    
    
    
    72,761Incremental shares from assumed conversions:Stock options and warrants
    
    
    2,201
    
    
    
    2,046
    
    
    
    1,911Preferred stock of National Welders (1)
    
    
    2,327
    
    
    
    
    
    
    
    Diluted shares outstanding
    
    
    81,152
    
    
    
    76,957
    
    
    
    74,672Diluted earnings per share from continuing operations
    
    $
    1.62
    
    
    $
    1.19
    
    
    $
    1.08Diluted earnings (loss) per share from discontinued
operations
    
    
    (0.02
    )
    
    
    0.01
    
    
    
    (0.01
    )Diluted loss per share from the cumulative effect of a
change in accounting principle
    
    
    (0.03
    )
    
    
    
    
    
    
    Diluted net earnings per share
    
    $
    1.57
    
    
    $
    1.20
    
    
    $
    1.07
 
 (1) - Pursuant to a joint venture agreement between the Company and the holders of the preferred
stock of National Welders, until June 30, 2009, the preferred shareholders have the option to
exchange their 3.2 million shares of National Welders voting redeemable preferred stock with a 5%
annual dividend either for cash at a price of $17.78 per share or to tender them to the joint
venture in exchange for approximately 2.3 million shares of Airgas common stock. If Airgas common
stock has a market value of $24.45 per share, the stock and cash redemption options are equivalent.(2) - If the preferred stockholders of National Welders convert their preferred stock to Airgas
common stock, the 5% preferred stock dividend, recognized as Minority interest in earnings of
consolidated affiliate, would no longer be paid to the preferred stockholders, resulting in
additional net earnings for Airgas.(3) - The earnings of National Welders for tax purposes are treated as a deemed dividend to Airgas,
net of an 80% dividend exclusion. Upon the assumed conversion of National Welders preferred stock
to Airgas common stock, National Welders would become a wholly owned subsidiary of Airgas. As a
wholly owned subsidiary, the net earnings of National Welders would not be subject to additional
tax at the Airgas level.(4) - The assumed conversion of National Welders preferred stock to Airgas common stock is not
presented because it was anti-dilutive.