<PAGE>
EXHIBIT 12.a
ONEOK, Inc.
Computation of Ratio of Earnings to Fixed Charges
<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
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Total Fixed Charges 22,605 68,343 55,413 37,400 37,514 37,728 40,057
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Earnings before income 98,117 168,306 169,552 168,380 94,107 85,873 68,146
taxes and income from
equity investees
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Earnings available for $ 120,722 $ 236,649 $ 224,965 $ 205,780 $ 131,621 $ 123,601 $ 108,203
fixed charges
====================================================================================================================================
Ratio of earnings to 5.34x 3.46x 4.06x 5.50x 3.51x 3.28x 2.70x
combined fixed charges
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Pro Forma Computation of Ratio of Earnings to Fixed Charges
Giving the Effect of 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
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Earnings before income 109,599 167,565
taxes and income from
equity investees
----------------------------------------------------------------
Earnings available for $ 136,398 $ 252,025
fixed charges
================================================================
Ratio of earnings to 5.09x 2.98x
combined fixed charges
================================================================
</TABLE>
For purposes of computing the ratio of earnings to fixed charges, "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.
