MPLX (MPLX) 8-K Other Events

Exhibit 12.1

MPLX LP

Computation of Ratio of Earnings to Fixed Charges

TOTAL ENTERPRISE BASIS - Unaudited

(In millions)

	For the Nine Months Ended September 30,		For the Years Ended December 31,
	2017		2016		2015		2014		2013		2012
Portion of rentals representing interest(1)	$	13	$	16	$	7	$	6	$	6	$	5
Capitalized interest		24		28		5		1		1		1
Other interest and fixed charges(2)		252		254		40		4		—		—
Total fixed charges (A)	$	289	$	298	$	52	$	11	$	7	$	6
Preferred dividend requirements	$	49	$	41	$	—	$	—	$	—	$	—
Ratio of income (loss) before provision for taxes to net income (loss)		1.0		1.0		1.0		1.0		1.0		1.0
Total preferred dividends	$	49	$	41	$	—	$	—	$	—	$	—
Combined fixed charges and preferred dividends (B)	$	338	$	339	$	52	$	11	$	7	$	6
Earnings-pretax income with applicable adjustments (C)	$	973	$	917	$	394	$	252	$	220	$	211
Ratio of (C) to (A)		3.4		3.1		7.6		22.9		31.4		35.2
Ratio of (C) to (B)		2.9		2.7		7.6		22.9		31.4		35.2

⁽¹⁾  Primarily related to interest incurred on operating leases.

⁽²⁾  Includes amortization of discounts on senior notes