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Exhibit 12.1

Main Street Capital Corporation
Computation of Ratio of Earnings to Fixed Charges
(dollars in thousands)

 
   Twelve Months Ended December 31,  
 
   2017   2016   2015   2014   2013  

Earnings:

                                

Net increase in net assets resulting from operations

   $ 170,622   $ 138,899   $ 104,437   $ 100,748   $ 96,855  

Income tax expense (benefit) and excise taxes

     24,471     (1,227 )   (8,867 )   6,287     (35 )
​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Total earnings before taxes

   $ 195,093   $ 137,672   $ 95,570   $ 107,035   $ 96,820  
​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Fixed Charges:

                                

Interest expense

   $ 36,479   $ 33,630   $ 32,115   $ 23,589   $ 20,238  
​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Total fixed charges

   $ 36,479   $ 33,630   $ 32,115   $ 23,589   $ 20,238  
​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Earnings available to cover fixed charges

   $ 231,572   $ 171,302   $ 127,685   $ 130,624   $ 117,058  

Ratio of earnings to fixed charges

     6.35     5.09     3.98     5.54     5.78  



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Main Street Capital Corporation Computation of Ratio of Earnings to Fixed Charges (dollars in thousands)