<PAGE>
 
                                  Exhibit 11
                                  ----------
                                        
                                      E-1
<PAGE>
 
                                                                      Exhibit 11
                                                                      
                                     INDEX
                                     -----

Calculation of earnings per share for the quarters and for the years ended
December 31:
 
                                                      PAGE
                                                      ----
 
                  o  1996                             E-3
 
                  o  1995                             E-4
 
                  o  1994                             E-5

                                     E-2 
<PAGE>
 
                                                                      Exhibit 11


                               LIFE TECHNOLOGIES
                       CALCULATION OF EARNINGS PER SHARE
                     for the year ended December 31, 1996
                    (amounts in thousands, except per share data)
                                     
<TABLE>
<CAPTION>
 
                                           Quarters (unaudited)
                                -------------------------------------------
PRIMARY                          First   Second    Third   Fourth    Year
---------------------------------------------------------------------------
<S>                             <C>      <C>      <C>      <C>      <C>
Net income                      $ 6,682  $ 8,295  $ 6,631  $ 7,092  $28,700 
                                ===========================================
 
Weighted average shares
  outstanding                    22,806   22,860   22,905   22,952   22,881
Weighted average effect of
  common stock equivalents          492      575      669      701      623
                                -------------------------------------------
                                 23,298   23,435   23,574   23,653   23,504
                                ===========================================
 
Primary net income per share    $   .29  $   .35  $   .28  $   .30  $  1.22
                                ===========================================
 
FULLY DILUTED
-------------
 
Net income                      $ 6,682  $ 8,295  $ 6,631  $ 7,902  $28,700
                                ===========================================

Weighted average shares
  outstanding                    22,806   22,860   22,905   22,952   22,881
Weighted average effect of
  common stock equivalents          533      663      729      759      793
                                -------------------------------------------
                                 23,339   23,523   23,634   23,711  $23,674
                                ===========================================
                                 
Fully diluted net income
 per share                      $   .29  $   .35  $   .28  $   .30  $  1.21
                                ============================================
</TABLE> 

All share and per share amounts have been adjusted for a 3 for 2 stock split
effected on August 28, 1996.

                                      E-3
<PAGE>
 
                                                                      Exhibit 11

                               LIFE TECHNOLOGIES
                       CALCULATION OF EARNINGS PER SHARE
                     for the year ended December 31, 1995
                    (amounts in thousands, except per share data)
                                     
<TABLE>
<CAPTION>
 
                                       Quarters (unaudited)
                                -----------------------------------
PRIMARY                         First    Second   Third   Fourth    Year
---------------------------------------------------------------------------
<S>                             <C>      <C>      <C>      <C>      <C>
 
Net income                      $ 5,622  $ 5,614  $ 5,367  $ 5,674  $22,277 
                                ===========================================
 
Weighted average shares
  outstanding                    22,494   22,547   22,617   22,743   22,601
Weighted average effect of
  common stock equivalents          197      283      395      404      328
                                -------------------------------------------
                                 22,691   22,830   23,012   23,147   22,929
                                ===========================================
 
Primary net income per share    $   .25  $   .25  $   .23  $   .25  $   .97  
                                ===========================================
 
FULLY DILUTED
-------------
 
Net income                      $ 5,622  $ 5,614  $ 5,367  $ 5,674  $22,277 
                                ===========================================
 
Weighted average shares
  outstanding                    22,494   22,547   22,617   22,743   22,601
Weighted average effect of
  common stock equivalents          224      351      480      507      522
                                -------------------------------------------
                                 22,718   22,898   23,097   23,250  $23,123
                                ===========================================
                                 
Fully diluted net income
 per share                      $   .25  $   .25  $   .23  $   .24  $   .96
                                ===========================================
</TABLE> 

All share and per share amounts have been adjusted for a 3 for 2 stock split
effected on August 28, 1996.

                                      E-4
<PAGE>
 
                                                                      Exhibit 11
                                                                      
                               LIFE TECHNOLOGIES
                       CALCULATION OF EARNINGS PER SHARE
                     for the year ended December 31, 1994
                 (amounts in thousands, except per share data)

<TABLE>
<CAPTION>
                                           Quarters (unaudited)
                                -------------------------------------------
PRIMARY                           First   Second    Third   Fourth    Year
---------------------------------------------------------------------------
<S>                             <C>      <C>      <C>      <C>      <C>
Net income                      $ 4,679  $ 4,638  $ 4,352  $ 4,538  $18,207
                                ===========================================
 
Weighted average shares
  outstanding                    22,439   22,455   22,461   22,470   22,457
Weighted average effect of
  common stock equivalents          153      131      155      158      150
                                -------------------------------------------
                                 22,592   22,586   22,616   22,628   22,607
                                ===========================================
 
Primary net income per share    $   .21  $   .21  $   .19  $   .20  $   .81
                                ===========================================

FULLY DILUTED
-------------
 
Net income                      $ 4,679  $ 4,638  $ 4,352  $ 4,538  $18,207
                                ===========================================
 
Weighted average shares
  outstanding                    22,439   22,455   22,461   22,470   22,457
Weighted average effect of
  common stock equivalents          153      165      195      248      239
                                -------------------------------------------
                                 22,592   22,620   22,656   22,718  $22,695
                                ===========================================
                                 
Fully diluted net income
 per share                      $   .21  $   .21  $   .19  $   .20  $   .80
                                ===========================================
</TABLE> 

All share and per share amounts have been adjusted for a 3 for 2 stock split
effected on August 28, 1996.

                                      E-5