Marketing metrics explained

What are impressions? Impressions and reach explained

An impression is one showing of an ad (or a post) on someone's screen, whether or not they notice it.

About the Meta Ads connector

Show the same ad to one person five times and you have five impressions and one person reached.

Impressions are the base of almost every other advertising metric. CPM is spend per thousand of them, CTR is clicks divided by them, and impression share is how many you got out of how many were available.

How it's calculated

Impressions are counted, not calculated: the platform adds one each time it shows the ad. Google Ads counts an impression each time an ad is shown on a search results page or another site on the Google Network, and notes that sometimes only part of the ad appears (Google Ads Help, Impressions: Definition).

The two figures people derive from them are reach and frequency:

• Reach is the number of different people who saw the ad at least once.
• Frequency is impressions ÷ reach: how many times, on average, each of those people saw it.

Meta Ads reports both, as Reach and Frequency, beside Impressions.

A campaign with 120,000 impressions and a reach of 40,000 has a frequency of 3.0. If it spent £960, its CPM was 960 ÷ 120,000 × 1,000 = £8.00.

What it tells you, and what it doesn't

Impressions tell you how much showing you bought. Reach tells you how many people that showing touched, and frequency tells you how hard you leaned on each of them. A rising frequency with flat reach usually means the audience is exhausted and the same people are seeing the ad again.

None of the three says anyone paid attention. An impression is a delivery receipt.

Where it goes wrong

Treating impressions as people. "Our ads were seen 120,000 times" and "120,000 people saw our ads" are different claims, and here the second is wrong by a factor of three.

Comparing impressions across platforms. Each platform decides what counts as a showing. Google's definition includes ads shown only in part; others have their own rules. Two platforms' impression counts are not measuring identical events, so compare cost and outcome per platform rather than raw volume.

Adding up reach. Reach is de-duplicated, so it does not sum. If Monday's reach was 10,000, Tuesday's 9,000 and Wednesday's 11,000, the three days together did not reach 30,000 people; many of Tuesday's were Monday's again. (These numbers are an illustration.) The same applies across campaigns that target overlapping audiences. Impressions can be summed safely; reach has to be asked for over the whole period in one go.

Related metrics

• CPM: the price of a thousand impressions.
• CTR: clicks as a share of impressions.
• Impression share: the impressions you won out of those you were eligible for.
• Marketing funnel: where impressions sit as the widest stage.

Keeping it current

A scheduled Fresh Sheets report can keep Meta Ads Impressions, Reach and Frequency by Campaign in a tab of its own, for example one called Meta Ads. Leave Day out of the report, so each campaign's reach covers the whole date range rather than being split into days.

Fresh Sheets replaces that tab's contents on every refresh, so keep your formulas on a separate tab. This total finds the column by its heading, so it still works if a field is added and the columns move:

=SUM(INDEX('Meta Ads'!A:Z, 0, MATCH("Impressions", 'Meta Ads'!1:1, 0)))