Impression share is the percentage of total available auctions in which your Google Ads appeared — out of all the auctions you were eligible for. A 50% impression share means your ads appeared in half of all auctions where they were eligible. The remaining 50% is 'lost' — either because of budget (you ran out of daily budget) or rank (your Ad Rank was not high enough to show). Google Ads reports both Lost IS (Budget) and Lost IS (Rank), allowing advertisers to identify whether to increase budget or improve Quality Score and bids.
Impression share is a diagnostic metric rather than a goal in itself. High impression share is only valuable if the impressions generate conversions at an acceptable CPA. A campaign with 90% impression share but poor conversion rates is not outperforming one with 40% impression share and excellent conversion rates. The correct use of impression share is as a ceiling diagnostic: if you are losing significant impression share due to budget, consider whether increasing budget will deliver proportional conversion volume at an acceptable CPA.
Impression share types and diagnostics
- Search Impression Share — your search ads' share of eligible search auctions
- Display Impression Share — your display ads' share of eligible display placements
- Search Lost IS (Budget) — impression share lost because daily budget was exhausted
- Search Lost IS (Rank) — impression share lost because Ad Rank was insufficient to show
- Exact Match IS — your share of eligible auctions for exact match versions of your keywords (excludes close variants)
- Absolute Top IS — percentage of impressions where your ad appeared in position 1
- Top IS — percentage of impressions where your ad appeared in the top positions (above organic results)
There is no universally 'good' impression share — it depends on campaign objectives and budget constraints. For brand search campaigns (targeting your own brand name), 90%+ impression share is the goal — you should dominate searches for your own name. For non-branded search campaigns, 40-70% impression share is often reasonable — higher IS typically requires either increased budget or bid/Quality Score improvements that may not deliver proportional conversion ROI. Aggressively chasing 100% impression share frequently results in diminishing returns.
Impression share lost to rank is caused by insufficient Ad Rank (bid × Quality Score). Improvements: increase keyword bids (direct effect on Ad Rank), improve ad relevance and landing page quality to improve Quality Score (indirect effect on Ad Rank), add relevant ad extensions (click-through rate signals improve Quality Score over time), and remove low-Quality-Score keywords dragging down campaign averages. Improving Quality Score is preferable to simply increasing bids — it improves Ad Rank at lower cost per impression.