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)

	Nine Months Ended,		For the Years Ended December 31,
	September 30, 2014		2013		2012		2011		2010		2009
Portion of rentals representing interest	$	2.6	$	3.3	$	2.3	$	0.8	$	0.7	$	0.5
Capitalized interest		0.7		0.9		0.7		0.5		0.7		0.7
Other interest and fixed charges		2.4		0.2		0.1		0.2		—		—
Total fixed charges (A)	$	5.7	$	4.4	$	3.1	$	1.5	$	1.4	$	1.2
Earnings-pretax income with applicable adjustments (B)	$	147.9	$	150.8	$	147.4	$	135.5	$	104.7	$	123.4
Ratio of (B) to (A)		25.9		34.3		47.5		90.3		74.8		102.8