Ad Frequency Calculator

Understanding the ad frequency calculator — concept and principle

Ad frequency tells you how many times, on average, each person in your audience saw your ad. Media planners use it with reach to judge whether a campaign is reaching enough people often enough without annoying them. This calculator gives the average frequency, checks it against your frequency cap and shows how many impressions your reach can absorb at that cap.

How it is calculated

• Average frequency = impressions ÷ unique reach.
• Status: "within your cap" when frequency is at or below the cap, otherwise "above your cap — risk of ad fatigue".
• Impressions at cap = unique reach × frequency cap.

Impressions are total ad views; unique reach is the number of distinct people (or accounts) who saw the ad at least once in the same period.

The principle

Impressions = reach × frequency is an identity: every impression lands on someone, so dividing total impressions by the number of different people gives the average views per person. It is only an average. Some people may have seen the ad once and others ten times, so a frequency of 5 can hide a heavy tail. Reach figures from ad platforms are usually modelled estimates, which also affects the result.

Worked example

1. Impressions 300,000 ÷ unique reach 60,000 = 5 average frequency.
2. 5 is not greater than the cap of 5, so the status is within your cap.
3. Impressions at cap = 60,000 × 5 = 300,000, exactly what was delivered, so any more spend on this audience would push it over the cap.

How to read the result

There is no universal ideal frequency. It depends on the goal, the creative, the channel and the length of the period. A frequency near 1 means wide but shallow exposure; a rising frequency with flat reach usually means the platform is showing the ad to the same people again. Watch click-through rate and cost per result as frequency rises: when they worsen, refresh the creative or widen the audience.

Common mistakes

• Mixing time windows, for example weekly reach with monthly impressions.
• Adding reach across campaigns or platforms; the same people overlap, so summed reach overstates unique people.
• Treating the average as the experience of every viewer.

Frequently asked questions

What is the difference between reach and impressions?

Reach counts distinct people; impressions count every time the ad was shown, including repeat views by the same person.

How do I set a frequency cap?

Most ad platforms let you limit impressions per person per day or week in the campaign or ad set settings. Test caps and watch performance.

Why did frequency jump late in my campaign?

Once most of the audience has been reached, extra budget is spent on people who already saw the ad, so frequency rises faster than reach.

Sources: Farris, Bendle, Pfeifer & Reibstein, Marketing Metrics, chapter on advertising media and web metrics (Pearson) · Interactive Advertising Bureau (IAB), glossary of interactive advertising terms