<PAGE>
 
                                                        Exhibit 11
                                                        ----------

                         SYNETIC, INC. AND SUBSIDIARIES
                       COMPUTATION OF EARNINGS PER SHARE
<TABLE>
<CAPTION>
 
                                                   QUARTERS ENDED     SIX MONTHS ENDED
                                                    DECEMBER 31,        DECEMBER 31,
                                                 ------------------  ------------------
                                                  1997      1996      1997      1996
                                                 -------  ---------  -------  ---------
<S>                                    <C>       <C>      <C>        <C>      <C>
 
Basic earnings(loss) from operations
  before extraordinary item..........  (A)       $ 1,937  $(25,934)  $ 3,429  $(23,545)
 
Assumed conversion of convertible
  debentures(1)......................                 -          -         -         -
                                                 -------   -------  --------  --------
 
Diluted earnings (loss) from operations
  before extraordinary item............. (B)     $ 1,937  $(25,934)  $ 3,429  $(23,545)
                                                 =======  ========   =======  ========

Basic earnings(loss) 
  from operations....................  (C)       $ 2,293  $(25,934)  $ 3,785  $(23,545)
 
Assumed conversion of convertible
  debentures(1)......................                 -          -         -         -
                                                 -------   -------  --------  --------
 
Diluted earnings (loss) 
  from operations......................  (D)     $ 2,293  $(25,934)  $ 3,785  $(23,545)
                                                 =======  ========   =======  ========
 
Weighted average shares
  outstanding - basic................  (E)        17,662    16,886    17,638    16,841
 
Common stock equivalents for
  dilutive earnings per
  share using the treasury
  stock method.......................              1,675        -      1,753         -
                                                 -------   -------  --------   -------
 
Additional equivalent shares upon
  assumed conversion of convertible
  debentures(1)......................                 -         -         -         -
                                                 -------   -------  --------   -------
 
Weighted average shares and common
  equivalent shares outstanding
  for diluted earnings per share.....  (F)        19,337    16,886    19,391    16,841
 
EARNINGS PER SHARE
 
Basic before extraordinary item......  (A)/(E)   $   .11  $  (1.54)  $   .19  $  (1.40)
 
Diluted before extraordinary item....  (B)/(F)   $   .10  $  (1.54)  $   .18  $  (1.40)

Basic................................  (C)/(E)   $   .13  $  (1.54)  $   .21  $  (1.40)

Diluted..............................  (D)/(F)   $   .12  $  (1.54)  $   .20  $  (1.40)

---------------------------
</TABLE>

(1) The Convertible Debenture conversion is not included in the computation of
    earnings per share as it is anti-dilutive for all periods presented.