Impression Share

Impression share is the percentage of impressions your ads received out of the impressions they were eligible to receive. Google's help page puts it as impressions divided by total eligible impressions, and notes that eligible impressions are estimated using many factors, including targeting settings, approval status, and quality. It is available in Google Ads for Search, Shopping, Performance Max, and Hotel campaigns, at campaign, ad group, product group, and keyword level, and Search Partners are not included. You find the columns in the campaign table under competitive metrics: search impression share, search lost IS (budget), and search lost IS (rank).

The estimate counts auctions where your ad showed and auctions where it was competitive enough to show. That makes it a view of the demand you could have reached, given your targeting. Google pairs it with two companion columns that split the missing share into reasons: share lost to budget, meaning your daily budget ran out while the ad was still eligible, and share lost to rank, meaning your ad rank was too low to win the auction. The lost-to-rank column reflects ad rank, which depends on your bid relative to competitors and on ad quality, so a low position can come from a weak ad as well as a low bid.

The companion columns tell you which fix to try. Mostly lost to budget means raising the budget or narrowing the targeting would capture more, assuming the campaign is profitable. Mostly lost to rank means improving the ad rank factors, such as bids, expected click-through rate, ad relevance, and landing page experience. Impression share also interacts with bid strategy. Target impression share is a bid strategy that sets bids to reach a chosen share, usually at the top of the page, and it can spend heavily. Changing match types or adding keywords alters the eligible pool, so the percentage moves for reasons unrelated to your bids. If you move from manual bidding to a target impression share strategy, you tell Google the share and position you want, and spending can climb fast if the target is aggressive, so cap the maximum bid.

Most mistakes involve chasing 100 percent. The last slice of impressions is the most contested and the least efficient, so paying for it often lowers return. Another error is judging a broad campaign by its overall figure when branded and generic keywords behave differently. Brand terms may sit above 90 percent for pennies while non-brand terms sit at 20 percent, and the blended number hides it. A third is reading a drop as failure when a competitor entered or search volume rose, since the denominator is moving. Check which keywords drive the average. A handful of brand terms with 95 percent can lift a campaign's share, while profitable generic terms sit at 15 percent without anyone noticing.

Look at impression share beside profit. For each campaign with good cost per conversion, check the lost-to-budget and lost-to-rank columns. If budget is the main loss and the campaign is profitable, raise the budget by a modest step and watch conversions per dollar. If rank is the loss, review quality factors before raising bids. This week, add all three columns to your campaign table, segment by device or day if volume allows, and write down one campaign where more share would clearly pay for itself and one where it would not. Use date ranges of at least a week, since single-day figures swing with competitor budgets.