<PAGE>   1
                                                                    EXHIBIT 12.1

                   SPIEKER PROPERTIES, INC. AND SUBSIDIARIES
                        COMPUTATION OF RATIO OF EARNINGS
               TO COMBINED FIXED CHARGES AND PREFERRED DIVIDENDS
                         (IN THOUSANDS, EXCEPT RATIOS)

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<CAPTION>
                                                                     Three Months Ended                Nine Months Ended 
                                                               ------------------------------    ------------------------------
                                                               September 30,    September 30,    September 30,    September 30,
                                                                   1997             1996             1997             1996
                                                               ------------------------------    ------------------------------
<S>                                                            <C>              <C>              <C>              <C>
Earnings:
  Income from operations before disposition of 
    property and minority interest                               $27,051          $16,096          $ 76,974          $48,207
  Interest expense(1)                                             16,214            9,761            40,914           26,443
  Amortization of capitalized interest                                87               61               260              182
                                                                 -------          -------          --------          -------   
  Total earnings                                                 $43,352          $25,918          $118,148          $74,832
                                                                 =======          =======          ========          =======   
Fixed charges:
  Interest expense(1)                                            $16,214          $ 9,761          $ 40,914          $26,443
  Capitalized interest                                             1,688              640             4,330            1,842
  Series A Preferred Dividends                                       573              524             1,146            1,573
  Series B Preferred Dividends                                     2,510            2,510             5,020            7,530
                                                                 -------          -------           -------          -------   
  Total fixed charges and preferred dividends                    $20,985          $13,435          $ 51,410          $37,388
                                                                 =======          =======          ========          =======   
Ratio of earnings to fixed charges
  (excluding preferred dividends)                                   2.42             2.49              2.61             2.65
                                                                 =======          =======          ========          =======   
Ratio of earnings to combined fixed charges
  and preferred dividends                                           2.07             1.93              2.30             2.00
                                                                 =======          =======          ========          =======   
Fixed charges in excess of earnings                              $    --          $    --          $     --          $    --
                                                                 =======          =======          ========          =======   


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Notes:
  (1) Includes amortization of debt discount and deferred financing fees.