EXHIBIT 12 SAFETY-KLEEN CORP. Ratio of Earnings to Fixed Charges ($ in thousands) (Unaudited) Three Months Ended Nine Months Ended May 31, May 31, ------- ------- 1999 1998 1999 1998 ---- ---- ---- ---- Income (loss) before income tax expense $ 50,653 $ (39,873) $ 130,325 $ (16,618) Add, Portions of rents representative of the interest factor 4,018 5,272 14,297 10,407 Interest on indebtedness, including amortization of deferred financing charges 42,551 31,777 132,256 61,266 ----------- ----------- ------------- ----------- Income as adjusted $ 97,222 $ (2,824) $ 276,878 $ 55,055 =========== ============ ============= =========== Fixed charges: Portions of rents representative of the interest factor $ 4,018 $ 5,272 $ 14,297 $ 10,407 Interest on indebtedness, including amortization of deferred financing charges 42,551 31,777 132,256 61,266 ----------- ----------- ------------- ----------- Total fixed charges $ 46,569 $ 37,049 $ 146,553 $ 71,673 =========== =========== ============= =========== Ratio of earnings to fixed charges 2.09x (0.08)x 1.89x 0.77x =========== ============ ============= ===========