Exhibit 12.1

CoStar Group, Inc.

Computation of Ratio of Earnings to Fixed Charges

	Three Months Ended June 30, 2017
				Years Ended December 31,
				2016			2015			2014			2013			2012
Earnings available for fixed charges:
Net income	$	22,184		$	85,071		$	-3,465		$	44,869		$	29,734		$	9,915
Income tax expense		3,611			51,591			6,046			26,044			17,803			13,219
Fixed charges excluding capitalized interest		7,545			17,349			16,554			16,881			12,219			9,672
Total earnings available for fixed charges		33,340			154,011			19,125			87,794			59,756			32,806
Fixed charges:
Interest expense		2,693			10,016			9,411			10,481			6,943			4,832
Rent deemed interest		4,852			7,333			7,133			6,400			5,276			4,840
Total fixed charges		7,545			17,349			16,544			16,881			12,219			9,672
Ratio of earnings to fixed charges		4.4	x		8.9	x		1.2	x		5.2	x		4.9	x		3.4	x