What Is Search Term Impression Share on Amazon?

How Amazon calculates SIS for a search term

SIS is calculated at the search query level. Amazon compares the impressions your ad campaign actually received for that query with the total potential impressions you could have received during the same period. It is reported as a percentage, so a higher number means your ad captured more of the available opportunities. Because the metric is query-specific, two campaigns targeting the same keyword can have different SIS values depending on bids, budgets, targeting settings, and relevance signals.

What a low or high impression share can indicate

A low SIS often points to missed visibility. The cause may be a daily budget cap, a bid that is not competitive enough, or an ad that is not relevant enough to win the auction consistently. A high SIS means your ad is present in a larger share of available placements, but it does not prove the search term is profitable. You should still look at orders, sales, ACoS, and conversion rate before deciding whether to scale or reduce exposure.

Changes over time are usually more informative than a single value. A falling SIS can be an early warning that performance is slipping before sales drop.

When search term impression share matters most

SIS is most useful when you manage competitive or high-priority search terms. If a term has historically produced strong orders and conversion, a drop in impression share can mean lost revenue. It is also helpful when launching a new campaign or entering a more competitive marketplace, because it can show whether your ad is gaining traction. Pairing SIS with search term data from a tool like Amazon Ads Dashboard by Todoza helps you see whether low visibility is tied to budget, bid, or targeting gaps.