EXHIBIT 12 PLAINS RESOURCES INC. COMPUTATION OF RATIOS Nine Months Ended September 30, -------------------- 1994 1995 1996 1997 1998 1998 1999 ------ ------ ------ ------ ------ ------ ------ RATIO OF EARNINGS TO FIXED CHARGES Earnings Net income (loss) before taxes and minority interest $ 571 $ 2,652 $17,754 $22,586 $ (99,465) $ 8,942 $38,024 Fixed charges 16,416 17,936 22,177 26,752 40,709 28,126 38,685 Less capitalized interest (2,728) (3,093) (3,613) (3,280) (3,683) (2,728) (3,203) ------- ------- ------- ------- --------- ------- ------- Total earnings available for fixed charges $14,259 $17,495 $36,318 $46,058 $ (62,439) $34,340 $73,506 ======= ======= ======= ======= ========= ======= ======= Fixed charges Interest expense $12,585 $13,606 $17,286 $22,012 $ 35,730 $24,385 $32,668 Capitalized interest 2,728 3,093 3,613 3,280 3,683 2,728 3,203 Interest portion on rentals 110 109 102 110 133 93 462 Amortization of debt issue costs 993 1,128 1,176 1,350 1,163 920 2,352 ------- ------- ------- ------- --------- ------- ------- Total fixed charges $16,416 $17,936 $22,177 $26,752 $ 40,709 $28,126 $38,685 ======= ======= ======= ======= ========= ======= ======= Earnings in excess of (required to cover) fixed charges $(2,157) $ (441) $14,141 $19,306 $(103,148) $ 6,214 $34,821 Earnings to fixed charges 0.9 1.0 1.6 1.7 (1.5)(A) 1.2 1.9 (A) Included in earnings for 1998 was a non-recurring gain of $60.8 million before income taxes relating to the formation of the partnership and a non-cash full cost ceiling writedown of $173.9 million before income taxes. If such events had not occurred, the ratio of earnings to fixed charges would have been 1.2.