Search Impression Share (SIS)
Definition
Search Impression Share (SIS) is a paid search metric that tells you how often your ads appear, compared to how often they could have appeared for your chosen keywords. To put it another way, it answers the question: “Out of every opportunity for my ad to show, how many times did it make the cut?” This metric is most often used in Google Ads because it measures visibility and helps to understand the actual competitiveness of a campaign.
Why It Matters
Understanding your Search Impression Share is crucial for maximising the effectiveness of your campaigns. A low impression share can signal that your ads aren’t showing as frequently as they could — often due to budget limits, low bids, or poor ad relevance. On the other hand, a high impression share means your brand is capturing a significant portion of available search traffic, increasing visibility, clicks, and ultimately conversions. Monitoring SIS allows advertisers to identify gaps in coverage and adjust strategy accordingly.
Example
Imagine you run a Google Ads campaign targeting “premium marketing agency in Ireland.” If your ads were eligible to show 1,000 times in a week but only appeared 600 times, your Search Impression Share would be 60%. This indicates that 40% of potential opportunities were missed, and adjusting your bids or budget could help capture a larger share of that market.
Additional Insights
Search Impression Share can be broken down into more detailed metrics. Lost Impression Share indicates the percentage of impressions your ads missed out on, which is often due to a limited budget or low ad rank. Absolute Top Impression Share reveals how often your ads secured the very top spot in search results. If you examine these figures together, you will gain a clearer picture of performance and be better informed to spend, improve reach, and drive campaigns towards stronger ROI.
Bottom Line
SIS is more than a vanity metric - it tells you how visible your brand really is in the search landscape. By improving SIS, you can appear more frequently in front of the right people, enhance campaign performance, and unlock growth opportunities that competitors may be overlooking.
