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TV Share (Share of Viewing)
TV Share is the percentage of all TV viewing in a given period that goes to one channel or platform, calculated against total TV viewing rather than the full population. It tells a planner how a channel is performing among people who are actually watching TV, independent of how many people are watching TV at all.
Formula
Worked example
During Czech prime time (19:00-22:00), adults 15-54, total average TV viewing audience across all channels is 2,100,000. TV Nova delivers an average audience of 630,000 in the same slot. Share = 630,000 / 2,100,000 x 100 = 30%. Nova holds 30% of all prime-time viewing among adults 15-54, regardless of the fact that only a fraction of the 15-54 universe was watching TV at all that evening.
How it is used
Buyers use share to judge a channel's competitive standing within a daypart or against a specific target, and to track erosion or growth independent of overall TV usage swings (holidays, weather, major sports events all move total viewing up or down for everyone). The mistake is treating share as if it were rating: a channel's share can rise while its actual audience falls, if total TV viewing falls faster than the channel's own audience does.
The common mistake
Don't compare share figures across different dayparts or days as if they represent absolute audience size; a 30% share at 8pm and a 30% share at 8am cover very different total viewing bases.