Impression

Paid Media

Also: Impressions · Ad Impression

What it isOne display of an ad or piece of content

CountsTimes shown, not people reached

Pairs withReach, frequency, CTR

Quick definition

An impression is a single instance of an ad or piece of content being shown. Every time your ad loads on a screen, that is one impression, whether or not the person notices it or clicks. Impressions count displays, not people, which is the distinction that trips most people up: one person can generate many impressions of the same ad.

Where it shows up in the data

Impressions versus reach

Impressions count displays. Reach counts distinct people. One person seeing an ad five times is five impressions and one reach. Confusing the two overstates how many people you touched.

Frequency

Impressions divided by reach gives frequency, the average number of times each person saw the ad. Too low and the message does not land, too high and you waste spend annoying people.

Viewability

An impression can be counted even if the ad never entered the visible screen area. Viewable impressions are the ones that actually had a chance of being seen, which is the number worth caring about.

What it actually means

An impression is logged each time an ad is served to a screen. It is the base unit of ad delivery and the denominator for a lot of other metrics. Cost per thousand impressions, or CPM, prices media by impressions. Click-through rate divides clicks by impressions. The critical thing to understand is that impressions are displays, not humans. If one person sees your ad ten times, that is ten impressions and one person. This is why impressions on their own are a vanity metric. They tell you how much your ad was shown, not whether it reached distinct people or moved them to act. Reach counts the distinct people, frequency counts how often each saw it and conversions count what happened.

Impressions count how many times an ad was shown, not how many people cared. It is the least meaningful number that everyone quotes first.

How it shows up

Impressions show up at the top of every ad platform report, usually as the largest number on the page. They feed CPM, which is how much you pay per thousand impressions, and click-through rate, which is clicks divided by impressions.

Where people get this wrong

Treating impressions as people reachedOne person can generate many impressions. Use reach for distinct people and impressions only for total displays, or you will badly overstate your audience.

Celebrating impression volume with no outcomeMillions of impressions and no clicks or conversions means you paid to be ignored. Impressions are an input, not a result.

Ignoring viewabilityA served impression is not always a seen impression. Ads can be counted below the fold or off screen. Look at viewable impressions to know what had a real chance of being noticed.

Common questions

What is an impression in marketing?

It is a single display of an ad or piece of content. Every time your ad loads on a screen it counts as one impression, whether or not the person notices or clicks. Impressions count displays, not people.

What is the difference between impressions and reach?

Impressions count how many times an ad was shown. Reach counts how many distinct people saw it. One person who sees an ad five times is five impressions and one reach.

Are impressions a good measure of success?

On their own, no. Impressions only tell you how often an ad was shown. Judge campaigns on reach, frequency and the actions they produce, and treat impressions as the raw input.

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About New Rebellion

New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.

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