Impression share - what it tells you and what to do when it is low

Impression Share has two components that matter: Impression Share Lost to Budget and Impression Share Lost to Rank. These are not interchangeable. Lost to budget means your daily budget ran out before all eligible searches were covered. Lost to rank means your Ad Rank was not high enough to win the auction. Each requires a different response, and confusing them leads to the wrong fix.

Lost to budget - the straightforward case

If a significant proportion of your impression share is lost to budget, your campaign is winning the auctions it enters but not entering all the auctions it could. The fix is to increase your daily budget. The calculation is simple: if your current budget is 50 pounds per day and you are losing 30 percent of impression share to budget, you need roughly 65 to 70 pounds per day to capture those additional impressions. Whether this is worthwhile depends on your current CPA and the margin on the additional volume you would generate.

The nuance is that not all lost impressions are equally valuable. If your impression share loss is concentrated during off-peak hours with historically low conversion rates, increasing budget to capture them may not improve CPA. Review lost to budget alongside performance by hour of day before deciding whether budget increase is the right response.

Lost to rank - the more complex case

Impression Share Lost to Rank means your ad is not winning auctions because your Ad Rank is insufficient. Ad Rank is determined by your bid, your Quality Score, and the expected impact of your extensions. Improving any of these improves Ad Rank and reduces rank-based impression share loss.

The right response depends on which component is limiting your rank. If your Quality Score is low, improving landing page relevance and ad copy relevance will improve Ad Rank without increasing bids. If your extensions are minimal, adding sitelinks, callouts, and structured snippets improves your expected extension impact and therefore your Ad Rank. Only after addressing these should you consider increasing bids, as bid increases without Quality Score improvement are an expensive way to improve rank.

Impression share benchmarks

There is no universal target for impression share. For brand campaigns, aiming for 90 percent or above is reasonable - you should be appearing for the vast majority of searches for your own brand. For non-brand competitive campaigns, 50 to 70 percent is a reasonable expectation. Pursuing 100 percent impression share on competitive non-brand terms requires bid levels that are rarely commercially justified.