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Glossary · Metrics

What is Impression share?

Also known as IS.

Definition

Impression share is the percentage of impressions you received out of the impressions you were eligible for. A 40% impression share means your ad appeared in four of every ten auctions it could have entered. Google splits the missing share into impression share lost to budget and lost to rank, which is what makes the metric actionable rather than merely interesting.

How it is calculated

Impression share = Impressions received ÷ Eligible impressions

What to know

The two loss reasons need opposite responses. Share lost to budget means the demand existed and you stopped paying for it. Share lost to rank means your bid, expected click-through rate or landing page quality was not competitive enough to enter the auction.

High impression share is not a goal in itself. Buying the last portion of a market usually means bidding into its least profitable queries, so we will not publish a target percentage. The right level is whatever still clears your CPA ceiling.

Related terms

Quality ScoreQuality Score is Google's 1 to 10 diagnostic of how relevant your keyword, ad and landing page are to a user's...CPCCPC (cost per click) is ad spend divided by clicks. It measures what you pay for attention, not for results. C...Bid strategyA bid strategy is the rule that decides what you pay for each auction. Manual strategies set a cost you contro...Search terms reportThe search terms report shows the actual queries people typed that triggered your ads, as opposed to the keywo...

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