Google Ads estimates how many impressions the ads were eligible to get on the Search Network. The estimate uses targeting, approval, bids and quality.
Impression share is the part of those eligible impressions that the ads got.
Lost to budget is the part that the ads did not get because the budget was too low.
Lost to ad rank is the part that the ads did not get because their Ad Rank was too low. Ad Rank depends on the bid, the ad quality, the Ad Rank thresholds and the context of each search.
What you can do
- For impressions lost to budget: before you increase the budget, check that the Campaign brings results at a cost that you accept.
- You can also remove spend from search terms and keywords that bring no results. The same budget can then cover more of the other eligible impressions.
- For impressions lost to ad rank: look at the bids and at the Quality score of the keywords on the page of the Campaign.
Data limitation: These shares are estimates by Google Ads. Google Ads gives no exact value when the impression share is under 10% or a loss is over 90%. The chart leaves those days out and states how many days it uses.