<PAGE>
 
                                                                    Exhibit 12-A

                        Delmarva Power & Light Company

                      Ratio of Earnings to Fixed Charges
                      ----------------------------------
                            (Dollars in Thousands)
                            ---------------------
<TABLE>
<CAPTION>
                                            12 Months
                                              Ended
                                            March 31,                              Year Ended December 31,
                                                           -------------------------------------------------------------------------
                                              1998             1997           1996           1995           1994           1993
                                        ------------------ -------------  -------------  -------------  -------------  -------------
<S>                                     <C>                <C>            <C>            <C>            <C>            <C>
Net income                                       $75,060       $105,709       $116,187       $117,488       $108,310       $111,076
                                        ------------------ -------------  -------------  -------------  -------------  -------------

Income taxes                                      51,782         72,155         78,340         75,540         67,613         67,102
                                        ------------------ -------------  -------------  -------------  -------------  -------------

Fixed charges:
    Interest on long-term debt
      including amortization of
      discount, premium and
      expense                                     79,587         78,350         69,329         65,572         61,128         62,651
    Other interest                                12,562         12,835         12,516         10,353          9,336          9,245
    Preferred dividend require-
      ments of a subsidiary
      trust                                        5,687          5,687          1,390             -              -              -
                                        ------------------ -------------  -------------  -------------  -------------  -------------
      Total fixed charges                         97,836         96,872         83,235         75,925         70,464         71,896
                                        ------------------ -------------  -------------  -------------  -------------  -------------

Nonutility capitalized interest                     (132)          (208)          (311)          (304)          (256)          (246)
                                        ------------------ -------------  -------------  -------------  -------------  -------------

Earnings before income taxes
    and fixed charges                           $224,546       $274,528       $277,451       $268,649       $246,131       $249,828
                                         =================  ============   ============   ============   ============   ============

Ratio of earnings to fixed charges                  2.30           2.83           3.33           3.54           3.49           3.47
</TABLE> 

For purposes of computing the ratio, earnings are net income plus income taxes
and fixed charges, less nonutility capitalized interest. Fixed charges consist
of interest on long- and short-term debt, amortization of debt discount,
premium, and expense, dividends on preferred securities of a subsidiary trust,
plus the interest factor associated with the Company's major leases, and one-
third of the remaining annual rentals.

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