QuickLinks -- Click here to rapidly navigate through this document


Exhibit 12.1


SM Energy Company
Ratio of Earnings to Fixed Charges

 
   
  Years ended December 31,  
 
  Nine months ended
September 30,
2011
 
 
  2010   2009   2008   2007   2006  
 
  (in thousands, except ratios)
 

Pretax income from continuing operations

  $ 531,269   $ 314,896   $ (159,464 ) $ 151,411   $ 300,262   $ 295,321  

Add: Fixed charges

   
41,250
   
29,558
   
31,702
   
25,029
   
26,060
   
12,601
 

Add: Amortization of capitalized interest

    3,055     2,991     2,697     2,349     1,719     1,022  

Less: Capitalized interest

    (6,569 )   (4,337 )   (1,902 )   (3,768 )   (5,410 )   (3,465 )
                           
 

Earnings before fixed charges

  $ 569,005   $ 343,108   $ (126,967 ) $ 175,021   $ 322,631   $ 305,479  
                           

Fixed charges:

                                     
 

Interest expense(1)

  $ 33,636   $ 24,196   $ 28,856   $ 20,275   $ 19,895   $ 8,521  
 

Capitalized interest

    6,569     4,337     1,902     3,768     5,410     3,465  
 

Interest expense component of rent(2)

    1,045     1,025     944     986     755     615  
                           

Total fixed charges

  $ 41,250   $ 29,558   $ 31,702   $ 25,029   $ 26,060   $ 12,601  
                           

Ratio of earnings to fixed charges

    13.8     11.6         7.0     12.4     24.2  

Insufficient coverage

  $   $   $ 158,669   $   $   $  

(1)
Includes amortization of discount and deferred financing costs.

(2)
Represents a reasonable approximation of the rental factor.



QuickLinks

SM Energy Company Ratio of Earnings to Fixed Charges