Impression Share / Advertising, Analytics Terms Impression Share Impression share is a metric used in digital advertising platforms, such as Google Ads and Microsoft Ads, to show the percentage of impressions your ad received compared to the total number of impressions it was eligible for. It helps advertisers understand how visible their ads are within their selected audience and keyword settings. A high impression share means your ads are appearing frequently, while a low impression share may suggest missed opportunities due to budget, competition or campaign structure. Impression share is calculated by dividing the number of impressions your ad received by the total number of impressions it could have received, based on your targeting, bids and quality score. For example, if your ad received 7,000 impressions out of 10,000 eligible impressions, your impression share is 70 percent. You can view impression share at the campaign, ad group or keyword level. Platforms also break this down further with metrics such as Search lost IS (budget) and Search lost IS (rank) to help diagnose why impressions may have been missed. Monitoring impression share helps advertisers identify underperforming areas and adjust strategies accordingly. If you have a high-performing keyword with low impression share, increasing your bid or budget may improve visibility. For brand awareness campaigns, aiming for a high impression share helps ensure your message reaches the full target audience. For B2B, e-commerce and nonprofit advertisers, impression share supports competitive analysis, budget planning and return on ad spend. It is especially useful when aiming to dominate high-intent searches or protect branded keywords.