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Lost impression share

Lost impression share is the share of impressions your ads were eligible for but did not get because the budget ran short or their Ad Rank was too low.

How it works

Google estimates how many impressions a campaign’s ads were eligible for. The share they got is the impression share; the rest is lost impression share, split by cause. Lost to budget means the ad was eligible, but the budget ran short. Lost to rank means its Ad Rank in the auction was too low.

Our guide to budget vs rank losses covers which of the two limits holds your store back.

Formula

Impressions missed for one cause ÷ impressions the ads were eligible for (both estimated by Google)

Where you see it

  • Google Ads reports: search budget lost impression share and search rank lost impression share for the Search Network; the Display Network has its own pair.
  • Shopping campaigns: the same Search pair; the Google Ads API also returns them per product.

Example

Example store, not client data.

The tableware shop’s search ads were eligible for an estimated 1,000,000 impressions in a month. They got 400,000, so impression share was 40%. Of the 600,000 missed, 150,000 were lost to budget (15%) and 450,000 to rank (45%).

Not to be confused with

  • Limited by budget — a yes-or-no campaign status. Lost impression share measures how much budget and rank each hold the campaign back.

Right and wrong readings

  • Wrong: “An impression share of 40% means we reach 40% of the market.” Right: the base is the impressions your own ads were eligible for, not every search in the market.
  • Wrong: “Lost to rank is 90%, so we miss exactly nine impressions in ten.” Right: Google reports these shares only up to 90% (anything higher is 0.9001 in the API), so 90% reads as “90% or more”.

Benchmarks

In GetProfit data (125 stores, June 2025 – June 2026), the median store won 45.8% of eligible search impressions. The medians for losses were 13.6% to budget and 50.2% to rank. Each median is taken on its own, so the three do not add up to 100%. Where both could be measured, rank was the bigger loss in 110 of 119 stores.

Impression share here describes each store’s own eligible pool, already limited by its catalogue and budget, not the size of the market. For Performance Max, it is incomplete. Your account may differ.

Sources

  • Metrics — Google Ads API: impression share and lost impression share, reported range. Checked 2 October 2026.
  • Shopping ads: Reporting — Google Ads API: lost impression share per product. Checked 2 October 2026.
  • GetProfit data: 125 stores, June 2025 – June 2026 — search impression share and its losses.