Proprietary ranking system that determines which products appear in Amazon search results and the order they are shown.
E-commerce sellers or marketers reading about optimizing product listings for Amazon's platform.
01What the A9 Algorithm Is and How It Works
The A9 algorithm (named after the original company Amazon acquired) is the core relevance and performance model powering Amazon's product search. It operates on two primary axes: relevance and performance. Relevance is measured by how well a listing's text — title, bullet points, description, and backend keywords — matches the exact words in a shopper's query. Performance is measured by historical click-through rate, conversion rate, sales velocity (often tracked via Best Sellers Rank), and customer feedback (star rating and review count). The algorithm combines these signals into a score for every product that meets the basic eligibility criteria (e.g., in-stock, category‑matched, not suppressed). Products with the highest scores appear first. The model is updated frequently based on new sales data and user behavior, so rankings can shift daily.
It's the hidden system Amazon uses to decide what products show up when you search, based on things like product names, sales volume, and customer ratings.
02What to Do About It — Actions You Can Take This Week
Improve your product listing’s relevance signals. Start with the title: place the primary keyword phrase at the front, but keep it readable. Complete all bullet points mentioning features and secondary keywords. Fill the backend search terms field with synonyms, misspellings, and related terms that are not in the visible listing. Use high‑resolution images and a clear product video to improve click‑through rate. Encourage early reviews through Amazon’s early reviewer program or Vine. Maintain inventory — being out of stock kills ranking. Run sponsored product ads (PPC) on the keywords you want to rank for, because organic and paid support each other; a product that converts from ads builds sales velocity that feeds the organic score.
03How the Algorithm Is Measured or Noticed
You cannot see the algorithm itself, but you can observe its output. The most direct metric is your product’s organic search rank for specific keywords. Use Amazon Brand Analytics (if you are a registered brand) to see the top search terms and your product’s click share. Alternatively, third‑party rank‑tracking tools approximate your position. Conversion rate (orders ÷ sessions) and click‑through rate from search are strong proxies — a rising conversion rate usually signals the algorithm is rewarding your listing. Best Sellers Rank (BSR), updated hourly, reflects sales performance relative to peers and correlates heavily with search position. Monitor changes in all these metrics after you update a listing to understand what the algorithm responded to.
04Common Mistakes
- Keyword stuffing in the title – A9 penalizes titles that are hard to read or irrelevant to the product category.
- Ignoring backend keywords – leaving the search terms field empty misses one of the easiest places to add extra relevant terms.
- Using irrelevant keywords to boost visibility – Amazon suppresses listings with high bounce rates when shoppers don't find what they expected.
- Buying or soliciting fake reviews – Amazon removes reviews and can suspend the selling account, destroying ranking.
- Poor image quality – low‑resolution or unclear images hurt click‑through rates, which lowers performance scores.
- Neglecting mobile formatting – most searches happen on mobile; if bullet points or images don’t render well, conversions drop.
- Going out of stock – even a short outage resets a product’s sales velocity, and rank takes days to recover.
- Creating duplicate listings for the same product – A9 may suppress both or merge them unpredictably.
05Limits and Misconceptions
The A9 algorithm only governs search results on Amazon.com and its international storefronts. It does not apply to Google, Bing, or other marketplaces. It is often confused with Google’s ranking algorithm, but the signals differ: Google cares about links and authority; Amazon cares about sales performance and conversion. Another common misconception is that A9 is a single, static formula. In reality, Amazon continuously adjusts it — what worked last month may not work today. Finally, the term "A9" is historically the internal name; Amazon now refers to its search system simply as "Amazon Search" or "product ranking," but the industry still uses "A9 algorithm" for clarity. The algorithm also does not control Amazon’s recommendation engine ("customers who bought this also bought"), which operates on collaborative filtering, not search ranking.
06Worked Example
A shopper searches for 'wireless bluetooth headphones' on Amazon. The A9 algorithm first finds all products with those words in the title, bullet points, and backend keywords. It then ranks them by performance. A product titled 'Wireless Bluetooth Headphones Over‑Ear with Microphone, 30‑Hour Battery' that has 500 reviews (4.5 stars), a conversion rate of 12%, and a low Best Sellers Rank (say #50 in Electronics) will appear on page one. A generic listing titled 'Earbuds' that contains the keywords only in the backend, with only 5 reviews and a high BSR, may appear on page five or beyond — even if both products are exactly the same item. The relevance match plus proven customer satisfaction determine the winner.
Frequently asked questions
What is the Amazon A9 algorithm?
The Amazon A9 algorithm is Amazon's proprietary ranking system that determines product visibility in search results. It evaluates factors like relevance, sales history, reviews, and listing completeness to match buyer queries with products.
How is the Amazon A9 algorithm different from Google's search algorithm?
The A9 algorithm is specific to Amazon's product search and focuses on purchase intent and conversion metrics, whereas Google's algorithm targets informational queries. A9 heavily weighs sales history and customer reviews, which are less relevant in Google search.
Should I focus on optimizing for the A9 algorithm if I sell on Amazon?
Yes, optimizing for the A9 algorithm is essential for visibility on Amazon. It directly affects your product's search ranking and sales. Without optimization, your products may be buried in search results.
How does the A9 algorithm determine product rankings?
The A9 algorithm uses relevance signals like title, description, and backend keywords, along with performance signals like sales velocity, click-through rate, and conversion rate. It scores products to determine the order in search results.
Does the A9 algorithm still use backlinks?
No, the A9 algorithm does not consider external backlinks like Google does. It focuses on on-listing optimization and product performance within Amazon. Off-site factors like social media don't directly influence A9 rankings.
Asked out loud
spoken, not typedThe same term in the words somebody uses speaking to an assistant rather than typing into a box — written from the situation, which is why each one carries the situation it came from.
It's usually due to the A9 algorithm updating rankings based on recent performance shifts. The algorithm values sales velocity, so a competitor may have surpassed you. Check your recent conversion rate and sales data.
It depends on how well you optimize for the A9 algorithm. You need to use relevant keywords in titles and bullet points, have compelling images, and start building sales through promotions or ads. Consistent optimization over time is key.
You're probably missing that the A9 algorithm heavily weights sales velocity and listing completeness. Good reviews alone are not enough. Check if the listing has proper backend keywords and if the product is priced competitively to drive conversions.