Definition Impression share runs between 0% and 100%. Lost share comes from budget caps or insufficient rank (Ad Rank). Google Ads reports these two loss types separately.
How it works The system evaluates ad eligibility per search session. Total eligible impressions are computed. Actual impressions are divided by eligible total. To recover budget-driven lost share, raise campaign budget. To recover rank-driven loss, improve bid, quality score, or ad extensions. The 100% upper bound is practically hard to reach.
Where you see it in Scope Trends **Ad Command Center** > **Impression Share** shows share and loss reasons at campaign and ad group level.
Frequently asked questions **Is low impression share always bad?** No. Low share is normal in niche targets. Review when share is under 60% on high-volume targets.
**Will raising max CPC increase impression share?** Yes for rank-driven loss. For budget-driven loss, raising CPC alone does not solve it.