<PAGE>
 
                                                                      EXHIBIT 11

              CHAMPION INTERNATIONAL CORPORATION AND SUBSIDIARIES

   CALCULATION OF PRIMARY EARNINGS (LOSS) PER COMMON SHARE AND FULLY DILUTED
                       EARNINGS (LOSS) PER COMMON SHARE

<TABLE>
<CAPTION>
                                                                 Years Ended December 31,
                                                     -----------------------------------------------

                                                         1996             1995             1994
                                                     -------------   ---------------   -------------
<S>                                                  <C>             <C>               <C>

   Net income (loss)                                  $   141,306    $      771,835     $    63,305
   Dividends on preference shares                             ---            13,258          27,750
                                                     -------------   ---------------   -------------

   Net income (loss) applicable to common stock       $   141,306     $     758,577     $    35,555
                                                     =============   ===============   =============

   Average number of common shares outstanding             95,524            94,725          93,061
                                                     =============   ===============   =============

   Per share                                           $     1.48     $        8.01     $       .38
                                                     =============   ===============   =============

Fully diluted earnings (loss) per common
 share (2,3):
   Net income (loss) applicable to common stock        $  141,306     $     758,577     $    35,555
   Add income effect, assuming conversion of
      dilutive convertible securities                         ---            15,106             ---
                                                     -------------   ---------------   -------------

   Net income (loss) on a fully diluted basis         $   141,306     $     773,683     $    35,555
                                                     =============   ===============   =============

   Average number of common shares outstanding             95,524            94,725          93,061

   Add common share effect, assuming conversion
      of dilutive convertible securities                      ---             6,171             ---
                                                     -------------   ---------------   -------------

   Average number of common shares outstanding
      on a fully diluted basis                             95,524           100,896          93,061
                                                     =============   ===============   =============

   Per share                                          $      1.48     $        7.67     $       .38
                                                     =============   ===============   =============
</TABLE> 
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Notes:
   (1)  Common stock equivalents have not been included in the above calculation
        since their effect is insignificant.

   (2)  The computation of fully diluted earnings per share assumes that the
        average number of common shares outstanding during the year is increased
        by the conversion of securities having a dilutive effect, and that net
        income applicable to common stock is increased by dividends and after-
        tax interest on such securities.

   (3)  Earnings per share was calculated for each three-month and twelve-month
        period on a stand-alone basis. On June 22, 1995, the company purchased
        all 7,894,737 shares of common stock that were issued on that date upon
        conversion of the $92.50 Cumulative Convertible Preference Stock. On
        June 27, 1995, the company called all $149,893,000 of its 6 1/2%
        Convertible Subordinated Debentures due April 15, 2011 for redemption on
        August 8, 1995. Virtually all of the Debentures were converted into an
        aggregate of 4,309,070 shares of common stock during the third quarter.
        The company purchased an additional 3,186,000 shares of common stock at
        various times during 1995. As a result of all of these transactions, the
        sum of the earnings per share for the four quarters of 1995 does not
        equal the earnings per share for the twelve months ended December 31,
        1995.