What Is the Reach & Frequency Calculator?
This calculator turns raw campaign numbers into the three metrics media planners care about most: reach (how many unique people saw your ad), frequency (how often they saw it on average), and GRP (Gross Rating Points, the total weight of the schedule). It works for TV, digital, social, and out-of-home campaigns — the math is universal.
How to Use It
Enter your total impressions (the count of all ad exposures), the number of unique people reached, and your target population (the audience size you express reach against). The tool returns reach as a percentage, the average frequency, and the resulting GRP.
The Formula Explained
Average frequency is simply impressions divided by reach: if 500,000 exposures land on 200,000 people, each person saw the ad 2.5 times on average. Reach percent is unique reach divided by the target population. GRP multiplies reach percent by frequency, giving a single figure that captures both how broadly and how repeatedly a campaign delivered.
$$\text{GRP} = \text{Reach \%} \times \text{Frequency}$$ $$\text{where}\quad \left\{ \begin{aligned} \text{Reach \%} &= \dfrac{\text{Reach}}{\text{Population}} \times 100 \\ \text{Frequency} &= \dfrac{\text{Impressions}}{\text{Reach}} \end{aligned} \right.$$
Worked Example
Suppose a campaign generated 500,000 impressions, reached 200,000 unique people, against a target population of 1,000,000. Frequency = \(500{,}000 / 200{,}000 = 2.5\). Reach % = \(200{,}000 / 1{,}000{,}000 = 20\%\). GRP = \(20 \times 2.5 = 50\) GRPs.
$$\text{Frequency} = \frac{500{,}000}{200{,}000} = 2.5$$ $$\text{Reach \%} = \frac{200{,}000}{1{,}000{,}000} \times 100 = 20\%$$ $$\text{GRP} = 20 \times 2.5 = 50 \text{ GRPs}$$FAQ
What is the difference between reach and impressions? Reach counts unique individuals; impressions count every exposure, so one person seeing an ad three times equals three impressions but a reach of one.
Are GRPs and TRPs the same? GRPs measure against the total population while TRPs (Target Rating Points) measure against a specific target demographic, but the multiplication is identical.
What frequency should I aim for? Many planners use an effective frequency of 3+ exposures for message recall, though it varies by goal, medium, and creative.
