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TV By the Numbers: March Madness Is a Slam Dunk for Viewership, Ad Impressions

Jalen Hawkins of the Norfolk State Spartans shoots during the first half against the Appalachian State Mountaineers in a First Four game during the NCAA Men's Basketball Tournament at Assembly Hall on March 18, 2021 in Bloomington, Indiana.
Jalen Hawkins of the Norfolk State Spartans shoots during the first half against the Appalachian State Mountaineers in a First Four game during the NCAA Men's Basketball Tournament at Assembly Hall on March 18, 2021 in Bloomington, Indiana. (Image credit: Stacy Revere/Getty Images)

This is a quick snapshot of TV by the numbers for the week of Mar. 15-21, revealing the most-watched shows and networks using glass-level data from Vizio’s Inscape, and the top shows and networks by TV ad impressions with insights via iSpot.tv.

Most-Watched Shows and Networks

Via Inscape, Vizio’s TV data product with glass-level insights from a panel of more than 17 million active and opted-in smart TVs. Data is linear, live TV only and includes all episode types (new and reruns). Rankings are by percent share duration (i.e., time spent watching).

March Madness captured the most watch-time during the week by far, accounting for 6.65% of all minutes, with 3.17% coming from games broadcast on CBS. Other sports-related programming that rose up the ranking included NBA basketball, PGA Tour golf and SportsCenter. Police procedurals Chicago P.D., Blue Bloods and NCIS moved up the chart, while shows that slipped week-over-week included Friends, Two and a Half Men, Home Town and The Voice

Also Read: NCAA March Madness Tourney Generating Record Ad Sales, Execs Say

Most-watched shows on TV by percent share duration for March 15-21.

The 2021 NCAA Basketball Tournament helped propel CBS into first place, with the network capturing 8.25% of all minutes watched during the week. March Madness also fueled a few other networks’ move up the ranking, including TBS (2.75% of watch-time), TNT (2.10%) and truTV (1.07%). Bravo got a slight bump up, taking No. 22 with 1.13% of minutes watched, thanks in part to reruns of Below Deck Mediterranean.

Most-watched networks on TV March 15-21

Top Shows and Networks by TV Ad Impressions

Via iSpot.tv, the always-on TV ad measurement and attribution company. Rankings are by TV ad impressions, for new episodes only. 

Thanks to March Madness, college basketball games generated an astounding 9.3 billion TV ad impressions — nearly as many as CBS had in total for new episodes (10.1 billion). It was the only programming to receive over a billion impressions for the week; Good Morning America took second place with 883.3 million, a 15.92% increase from the previous week. The Bachelor saw an 81.89% week-over-week increase in impressions, up to 567.4 million, while The Voice’s 430.6 million impressions constituted a 26.76% decrease from the previous week.

Top shows by TV ad impressions for March 15-21

CBS had nearly twice as many TV ad impressions (10.1 billion) as the second-place network, ABC (5.2 billion), and half of those impressions came from college basketball. MSNBC saw a 59.73% increase in impressions week-over-week, up to 3.1 billion and edging out CNN (2.5 billion impressions). After a week off the ranking, TBS came back strong with 2.3 billion impressions, primarily fueled by March Madness games. TNT and truTV also benefited from the tournament, with 1.5 billion and 840 million impressions, respectively.

Top networks by ad impressions March 15-21