Frequency Cap Calculator
Convert impressions and reach into average frequency, then see what a cap actually does — it converts depth into breadth, and only if it sits BELOW your current average.
Frequency Cap Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Average frequency conceals a skewed distribution.
- Assumes freed impressions can actually find new unique people.
- Decay is modelled at a constant rate per exposure.
In short: A cap above your average does nothing at all. At 1,000,000 impressions and 285,000 reach the frequency is 3.5088; capping at 3 frees 145,000 impressions and lifts reach 16.9591%, while capping at 4 frees exactly zero.
Formula
frequency = impressions ÷ reach
freed impressions = impressions − (reach × cap)
[('frequency', 'average exposures per person reached'), ('cap', 'binds only when BELOW the current average'), ('freed', 'impressions redeployable to new people'), ('effective frequency', 'the floor below which nobody remembers')]
Worked Example
- Divide impressions by unique reach for average frequency.
- Check the cap actually sits below that average.
- Compute the impressions the cap frees.
- Divide by the cap for the additional people reachable.
- Confirm you are still above the effective frequency floor.
1,000,000 impressions across 285,000 people is an average frequency of 3.5088, costing 0.0876 per person reached. A cap of 3 limits delivery to 855,000 impressions, freeing 145,000 — enough to reach 48,333 additional people and lift total reach to 333,333, a 16.9591% gain for the same 24,975. A cap of 4 would free exactly zero, because it sits above the 3.5088 average. At 12% decay the 4th exposure performs at 1.2607% against 1.8500% on the first.
Strengths & Limits Of This Model
Where this engine is strong
- States plainly when a cap binds on nobody
- Converts freed impressions into additional reach
- Warns when capping would fall below the effective floor
Where it stops
- Averages hide distribution
- Constant decay assumed
Practical Use Cases
Setting a frequency cap
Checking the cap will actually bind.
Trading depth for breadth
Redeploying impressions to new people.
Diagnosing creative fatigue
Valuing the decay across exposures.
Reach planning
Converting a budget into unique people.
Avoiding over-capping
Confirming you stay above the effective floor.
Methodology & Editorial Standards
Average frequency is impressions over unique reach. A cap is applied as reach multiplied by the cap, so it binds only when it sits below the current average — and where it does not, the page says so explicitly rather than reporting a zero and leaving the user to work out why. Freed impressions are converted into additional reachable people at the capped rate, and the result is tested against an effective frequency floor because capping below that floor destroys effect rather than improving efficiency.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Frequency Cap Calculator — 10 Expert FAQs
10 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
How do you calculate frequency?
Divide impressions by unique reach. Three million impressions across one million people is a frequency of three. It is an average, and the distribution behind it is usually skewed with a minority of the audience absorbing a disproportionate share.
What is a good frequency?
Enough for the message to register and not so much that it irritates. Classical planning suggests a floor of around three exposures before a message is remembered, with diminishing and eventually negative returns beyond roughly seven — though the right window varies by objective and by medium.
Does a frequency cap reduce my spend?
No, it redistributes it. The budget still spends; it simply reaches more people fewer times each. That is the trade a cap makes, and it is only an improvement if you are above the effective frequency floor to begin with.
Why did my frequency cap do nothing?
Almost always because it sits above your current average. A cap of five against an average of three binds on almost nobody. To change delivery the cap must be below the average you already have, which is the single most common error in setting one.
What is effective frequency?
The number of exposures needed before a message is registered and acted on. Below it, additional reach produces impressions nobody remembers, so spreading a thin campaign thinner actively destroys its effect. Capping below the effective floor is worse than not capping.
What is frequency decay?
The observed fall in response with each additional exposure to the same person. The first impression does the most work and each subsequent one does measurably less, which is the underlying economic argument for capping rather than an aesthetic objection to repetition.
Should I cap on impressions or on time?
Both, ideally — most platforms allow a cap of N impressions per period. A cap of three per week behaves very differently from three per campaign, and the period matters as much as the number when the flight runs for months.
Does frequency matter for search advertising?
Far less, because search is intent-driven and the user initiates each impression. Frequency management is primarily a display, video and social concern, where you are interrupting rather than answering.
How does frequency affect cost per thousand?
It does not change the CPM, which is exactly the problem. You pay the same price for the tenth impression to the same person as for the first, despite it being worth far less. Cost per person reached is the metric that exposes this; CPM conceals it.
Can frequency be too low?
Yes, and it is the failure mode of chasing reach. A campaign spread so thinly that nobody sees it more than once buys impressions that leave no trace. Reach without sufficient frequency is measurable delivery and immeasurable effect.