<PAGE>
EXHIBIT 12
ONEOK, Inc.
Computation of Ratio of Earnings to Combined Fixed Charges
and Preferred Stock Dividend Requirements
<TABLE>
<CAPTION>
Three Months Year Ended Years Ended August 31,
Ended December 31, --------------------------------------------------------------------
March 31, 2000 1999 1999 1998 1997 1996 1995
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(Thousands of Dollars)
<S> <C> <C> <C> <C> <C> <C> <C>
Fixed Charges, as defined
Interest on long-term $ 16,220 $ 44,786 $ 37,087 $ 30,846 $ 31,354 $ 31,748 $ 32,345
debt
Other interest 5,151 18,993 14,440 3,723 3,376 3,184 4,934
Amortization of debt 614 1,960 1,282 506 518 530 512
discount and expense
Interest on lease 620 2,604 2,604 2,325 2,266 2,266 2,266
agreements
--------------------------------------------------------------------------------------------------------------------------------
Total Fixed Charges 22,605 68,343 55,413 37,400 37,514 37,728 40,057
Preferred dividend 14,960 59,971 61,061 44,228 285 428 428
requirements
--------------------------------------------------------------------------------------------------------------------------------
Total fixed charges and $ 37,565 $ 128,314 $ 116,474 $ 81,628 $ 37,799 $ 38,156 $ 40,485
preferred dividend
requirements
================================================================================================================================
Earnings before income $ 98,117 $ 168,306 $ 169,552 $ 168,380 $ 94,107 $ 85,873 $ 68,146
taxes and income from
equity investees
Total fixed charges 22,605 68,343 55,413 37,400 37,514 37,728 40,057
--------------------------------------------------------------------------------------------------------------------------------
Earnings available for $ 120,722 $ 236,649 $ 224,965 $ 205,780 $ 131,621 $ 123,601 $ 108,203
combined fixed
charges and preferred
dividend requirements
================================================================================================================================
Ratio of earnings to 3.21x 1.84x 1.93x 2.52x 3.48x 3.24x 2.67x
combined fixed charges and
preferred dividend
requirements
================================================================================================================================
Pro Forma Computation of Ratio of Earnings to Combined Fixed Charges and
Preferred Stock Dividend Requirements
Giving Effect to the Acquisition Discussed Herein
Three Months Year Ended
Ended December 31,
March 31, 2000 1999
----------------------------------------------------------------
(Thousands of Dollars)
Fixed Charges, as defined
Interest on long-term $ 19,354 $ 57,321
debt
Other interest 5,151 18,993
Amortization of debt 614 1,960
discount and expense
Interest on lease 1,680 6,186
agreements
----------------------------------------------------------------
Total Fixed Charges 26,799 84,460
Preferred dividend 14,960 59,971
requirements
----------------------------------------------------------------
Total fixed charges and $ 41,759 $ 144,431
preferred dividend
requirements
================================================================
Earnings before income $ 109,599 $ 167,565
taxes and income from
equity investees
Total fixed charges 26,799 84,460
----------------------------------------------------------------
Earnings available for $ 136,398 $ 252,025
combined fixed
charges and preferred
dividend requirements
================================================================
Ratio of earnings to 3.27x 1.75x
combined fixed charges and
preferred dividend
requirements
================================================================
</TABLE>
For purposes of computing the ratio of earnings to combined fixed charges and
preferred dividend requirements, "earnings" consists of income before cumulative
effect of a change in accounting principle plus fixed charges and income taxes,
less undistributed income from equity investees. "Fixed charges" consists of
interest charges, the amortization of debt discounts and issue costs and the
representative interest portion of operating leases. "Preferred dividend
requirements" consists of the pre-tax preferred dividend requirement.
