Performance

Impression share

Also known as: IS · search impression share

Definition

Impression share is the percentage of impressions an ad received out of the total it was eligible to receive, as estimated by Google Ads. It shows how much available demand a campaign is capturing and whether budget or ranking is the reason for the rest.

Google defines it as impressions divided by total eligible impressions, and the missing share has two causes. Share lost to budget means the campaign ran out of daily money while demand was still there. Share lost to rank means Ad Rank was too low to win the auction. They need different fixes, so read both columns before changing anything.

Chasing full share is rarely sensible, because the last slice of impressions usually costs the most. Set targets by campaign type: near-complete share on your own brand name, deliberately lower on broad service terms. A workable rule: if lost-to-budget is high on a campaign whose cost per conversion beats your target, raise the budget, and if lost-to-rank is high, fix quality before bids. The auction insights report shows who you're meeting, including the week a new competitor starts bidding on your name.

Formula

Impression share = Impressions ÷ Total eligible impressions

More in Performance

A/B testing

A/B testing compares two versions of one element, such as a headline, an offer or a page, by showing each to a randomly split share of traffic at the same time and measuring which produces more conversions. It needs enough traffic and one change at a time.

Ad fatigue

Ad fatigue is the decline in an ad's performance as the same people see it repeatedly, usually visible as rising frequency and falling click-through rate before cost per result climbs. The remedy is fresh creative or a wider audience, not a bigger budget.

Ad Rank

Ad Rank is the value Google Ads calculates in each auction to decide whether an ad is eligible to show and where it sits against others. It combines the bid with ad and landing page quality, minimum thresholds, competition, search context and the expected impact of assets.