Impression share is the impressions your ads received as a proportion of the impressions they were eligible to receive. Sixty per cent means that for every ten auctions you could have been in, you appeared in six.
Google splits what you lost into two columns, and on a grant account they mean almost opposite things.
- Lost to rank: you were eligible and were beaten. At a $2 ceiling that is nearly always a quality problem, and it is the column to work on.
- Lost to budget: the campaign ran out of its daily budget. On a grant account with the whole $10,000 unspent, this usually means a daily budget set far below what the campaign could use.
What it is good for, and what it is not
It is the clearest answer to “why is this campaign quiet”. It is a poor target in itself: chasing impression share on a grant account means buying impressions, and impressions without clicks are the thing that moves the click-through rate in the wrong direction.
Questions people ask
What is a good number?
There is no good number. Read it beside click-through rate and conversions: high share with a weak rate is an account buying the wrong impressions.
Why is mine so low on a brand-name search?
Eligibility includes things outside the auction — targeting, scheduling, the hours a budget lasted. Check those before concluding you were beaten.
Lost to budget on a grant account?
Look at the daily budgets. The grant is a monthly ceiling, and a campaign capped far below its share of it will report exactly this.