Impression share is the percentage of impressions your ads received out of the total they were eligible to receive. If Google estimates your ads could have appeared 1,000 times for the searches you target, and they appeared 400 times, your impression share is 40%.
How impression share works
Eligibility is judged from your own settings: your keywords, locations, schedule, devices and approval status. Searches outside your targeting do not count. Google then estimates how many times you could have shown and divides your actual impressions by that number. Because it is an estimate, the figure is approximate, and very low or very high values are shown as “<10%” or “>90%” rather than exact numbers.
The metric comes with two companions that explain what you missed:
- Lost impression share (budget): the share of eligible impressions missed because your daily budget ran out or Google held spend back to pace it.
- Lost impression share (rank): the share missed because your Ad Rank was too low to win a place, a mix of bid, ad quality and expected landing page experience.
Impression share plus the two lost figures adds up to roughly 100%. Search campaigns also report top and absolute top impression share, which measure how often you appeared above the organic results and in the very first ad position.
The figures are available for Search, Shopping and Display campaigns, and at keyword level for Search. They are found under the Competitive metrics columns and are usually a day or two behind.
Why it matters
Clicks and conversions tell you what happened. Impression share tells you what you missed. A London accountant whose campaign produces steady enquiries at 35% impression share, with most of the loss down to budget, has a clear choice: there is more demand available at roughly the same cost per lead, if the business can handle the work.
It also stops a common wrong move. If most of your loss is to rank, adding budget does almost nothing, because the campaign is not running out of money; it is losing auctions. The fix there is better ads, better landing pages, tighter keywords or higher bids.
For brand campaigns, a high impression share on your own name is usually cheap and worth having, so a competitor bidding on your name does not take the top spot.
Common mistakes
- Treating 100% as the goal. The last few percent of impressions can be the most expensive, often on searches that convert least.
- Reading impression share without the lost columns, so you do not know whether budget or rank is the problem.
- Raising the budget on a campaign that is limited by rank.
- Judging a whole campaign’s share when only a few high-value keywords matter. Check those at keyword level.
- Choosing the target impression share bid strategy for non-brand terms without a maximum bid cap, which can push cost per click up sharply.
How to act on it
Add the impression share, lost (budget) and lost (rank) columns to your campaign view and look at the last 30 days. If budget loss is large and the campaign is profitable, increase the budget in steps, or narrow the targeting so the same money covers the best searches. If rank loss is large, work on ad relevance, landing page experience and bids for your most valuable keywords.
Then open Auction insights to see which competitors appear most often alongside you. I use this reading every month when running Google search campaigns, because it shows whether the next pound is better spent on budget, bids or the page itself.