Reference library · Media planning
Rating (%)
Rating is the percentage of a defined target universe (e.g. adults 18-54) exposed to a specific program, spot, or daypart at a given moment, measured against the total population in that universe, not against the number of people currently watching TV. It is the atomic unit that every GRP and TRP figure is summed from.
Formula
Worked example
Czech market, target 15-54, total universe 5,200,000 people. A prime-time program is watched by 260,000 of them: Rating = 260,000 ÷ 5,200,000 × 100 = 5.0%. That single spot contributes 5.0 rating points toward the plan's TRP total; a flight of 20 such spots at similar levels builds toward 100 TRPs.
How it is used
Planners pull average program or daypart ratings from panel data (people-meters or panel-based diaries) and sum them across the flight to get GRP/TRP, then derive reach and frequency from that base. The recurring mistake is treating rating and share as interchangeable: share divides by the number of people watching TV at that moment (PUT/HUT), while rating divides by the entire target universe including everyone not watching. A program can hold a high share in a dead daypart and still post a low rating.
The common mistake
Rating and share get swapped because both are percentages of viewing, but rating's denominator is the whole target universe while share's denominator is only those watching TV right then.