<PAGE>

                                                                    EXHIBIT 12.1

                       W. R. GRACE & CO. AND SUBSIDIARIES
              COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES AND

            COMBINED FIXED CHARGES AND PREFERRED STOCK DIVIDENDS (a)
                          (in millions, except ratios)

                                   (Unaudited)


<TABLE>
<CAPTION>
                                                         Six Months Ended
                                                             June 30,
                                                      ---------------------                Year Ended December 31, (c)
                                                        1999       1998       1998(d)    1997(e)    1996(f)    1995(g)     1994(h)
                                                        ----       ----       -------    -------    -------    -------     -------
<S>                                                     <C>        <C>       <C>          <C>      <C>         <C>        <C>
Net income/(loss) from continuing operations            $51.4      $37.3     $(145.7)     $88.2    $ 112.9     $(324.8)   $(185.4)
   Add/(deduct):
   Provision for/(benefit from) income taxes             30.2       23.9       (69.0)      55.2       70.4      (192.4)    (120.9)

   Equity in unremitted (earnings)/losses of less
     than 50%-owned companies......................      (1.0)      (4.6)      (10.8)      (7.0)       (.4)         .8        (.6)

   Interest expense and related financing costs,
     including amortization of capitalized interest      10.2       25.3        37.9       93.7      169.8       183.5      145.5

   Estimated amount of rental expense deemed
     to represent the interest factor..............       3.3        2.8         5.2        6.9        8.4         8.5       10.1
                                                        -----      -----     -------      -----    -------     -------    -------

Income/(loss) as adjusted..........................     $94.1      $84.7     $(182.4)   $ 237.0    $ 361.1     $(324.4)   $(151.3)
                                                        =====      =====     =======      =====    =======     =======    =======

Combined fixed charges and preferred stock dividends:
   Interest expense and related financing costs,
     including capitalized interest................     $ 9.4      $24.6       $37.8      $98.5    $ 186.1     $ 199.2    $ 150.2

   Estimated amount of rental expense deemed
     to represent the interest factor..............       3.3        2.8         5.2        6.9        8.4         8.5       10.1
                                                        -----      -----     -------      -----    -------     -------    -------

Fixed charges......................................      12.7       27.4        43.0      105.4      194.5       207.7      160.3

Preferred stock dividend requirements (b)..........        --         --          --         --         .6          .5         .5
                                                        -----      -----     -------      -----    -------     -------    -------


Combined fixed charges and preferred stock dividends    $12.7      $27.4       $43.0     $105.4    $ 195.1     $ 208.2    $ 160.8
                                                        =====      =====     =======      =====    =======     =======    =======

Ratio of earnings to fixed charges.................      7.41       3.09         (i)       2.25       1.86         (i)        (i)
                                                        =====      =====     =======      =====    =======     =======    =======

Ratio of earnings to combined fixed charges and
     preferred stock dividends.....................      7.41       3.09         (i)       2.25       1.85         (i)        (i)
                                                        =====      =====     =======      =====    =======     =======    =======


</TABLE>

(a)  Grace's preferred stocks were retired in 1996; for additional information
     see Note 1 to the Consolidated Financial Statements in the 1998 10-K.

(b)  For each period with an income tax provision, the preferred stock dividend
     requirements have been increased to an amount representing the pretax
     earnings required to cover such requirements based on Grace's effective tax
     rate.

(c)  Certain amounts have been restated to conform to the 1998 presentation.

(d)  Includes a pretax provision of $376.1 million for asbestos-related
     liabilities and insurance coverage; $21.0 million relating to restructuring
     costs and asset impairments, offset by a pretax gain of $38.2 million for
     the receipt of insurance proceeds related to environmental matters,
     partially offset by a charge to reflect a change in the environmental
     remediation strategy for a particular site.

(e)  Includes a pretax gain of $103.1 million on sales of businesses, offset by
     a pretax provision of $47.8 million for restructuring costs and asset
     impairments.

(f)  Includes a pretax gain of $326.4 million on sales of businesses, offset by
     pretax provisions of $229.1 million for asbestos-related liabilities and
     insurance coverage and $34.7 million for restructuring costs and asset
     impairments.

(g)  Includes pretax provisions of $275.0 million for asbestos-related
     liabilities and insurance coverage; $151.3 million relating to
     restructuring costs, asset impairments and other activities; $77.0 million
     for environmental liabilities at former manufacturing sites; and $30.0
     million for corporate governance activities.

(h)  Includes a pretax provision of $316.0 million relating to asbestos-related
     liabilities and insurance coverage.

(i)  As a result of the losses incurred for the years ended December 31, 1998,
     1995 and 1994, Grace was unable to fully cover the indicated fixed charges.