Audience breadth
People or percent exposed at least once
Measurement guide · Audience distribution
Reach, frequency and GRP are connected—not interchangeable
Reach describes how many people were exposed at least once; average frequency describes repetition among those reached.
Average repetition
Among the audience reached
Gross rating points
Reach percentage × frequency
Verified record
What the sources support.
Claims below reproduce the scope of the page contract. Derived items show their calculation.
- verified
Geopath defines reach as the number or percentage of a target audience exposed at least once and frequency as the average number of exposures among those reached.
- verified
The MRC public-comment draft says OOH measurement techniques vary by format and location and that inherent limitations should be studied and disclosed.
- derived
GRP can be derived as reach percentage multiplied by average frequency.
GRP = Reach (%) × Average frequency
01 / Analysis
The definitions
Geopath defines reach as the number or percentage of a target audience exposed at least once. Frequency is the average number of exposures among those reached.
02 / Analysis
Worked example
Illustration: if a plan reaches 60% of its target audience at an average frequency of 3, the derived GRP is 180. If the target audience contains 100,000 people, 60,000 are reached and the implied gross impressions are 180,000. These are arithmetic examples, not campaign benchmarks.
03 / Analysis
Where comparison fails
Two plans with the same GRP can distribute exposure differently. The underlying impression method, target universe, geography, time period and duplication rules must align before the numbers are comparable.
Source desk
Sources for this page
- GeopathCurrent fundamentals pageMeasurement Fundamentals: Reach and Frequency (opens in a new tab) ↗
Used for: Definitions of reach and average frequency in OOH audience measurement.
- Media Rating CouncilNovember 2023 draftOOH Measurement Standards — Public Comment Draft (opens in a new tab) ↗
Used for: OOH measurement terms, format-dependent techniques and disclosure of limitations.