How the Amazon A9 Algorithm Ranks Products

At Lillian Purge, we specialise in Ecommerce SEO Services and have developed comprehensive guidance on How pricing impacts rankings in Amazon search results.

The A9 algorithm is Amazon’s proprietary search and ranking system that decides which products appear when a customer searches for an item. Its goal is simple: show the listings most likely to result in a sale.

Unlike Google, which focuses on relevance and authority, Amazon’s algorithm prioritises sales performance and customer experience. In other words, A9 rewards listings that not only match search intent but also demonstrate a proven ability to convert. The more a product sells after appearing in search results, the more Amazon’s system learns to rank it higher.

A9 uses machine learning to evaluate a wide range of signals, from keywords and pricing to customer feedback and fulfilment speed. Understanding these signals is crucial to improving your product visibility and overall revenue.

How the Amazon A9 algorithm works

When a user types a query, A9 analyses millions of listings to decide which ones are most relevant. It follows three core stages:

1. Relevance filtering – The algorithm filters products based on keywords and category data. Listings that don’t include the searched terms in titles, descriptions, or backend keywords are excluded.

2. Performance scoring – A9 then evaluates listings by sales history, conversion rate, pricing, and reviews. Products that generate consistent sales get priority.

3. Customer experience weighting – Finally, the algorithm factors in fulfilment method, return rate, and shipping speed to ensure a positive buyer experience.

The system constantly updates, meaning sellers must maintain high-quality listings and strong metrics to remain competitive.

Key factors influencing A9 ranking

Several ranking factors determine where your products appear in Amazon’s search results. These can be grouped into relevance, performance, and customer satisfaction signals.

1. Keyword relevance

Keywords are the foundation of A9. The algorithm analyses your titles, bullet points, descriptions, and backend search terms to determine if your listing matches the user’s query.

• Title optimisation – Include your main keyword naturally within the first few words of the product title.

• Bullet points and descriptions – Use supporting keywords to reinforce relevance without keyword stuffing.

• Backend keywords – Fill in the hidden search term fields in Seller Central with variations and alternative phrases.

Accurate keyword placement ensures your product appears for relevant searches and avoids being filtered out.

2. Sales performance

Amazon’s ultimate goal is to promote listings that drive conversions. A strong sales history signals high buyer trust and demand, which directly boosts rankings.

• Conversion rate – If users frequently buy your product after viewing it, Amazon sees it as valuable and ranks it higher.

• Click-through rate (CTR) – Listings with appealing images and titles attract more clicks, which can improve position.

• Sales velocity – Consistent or increasing sales momentum helps sustain visibility.

Sellers who focus on optimising listings and pricing to maximise conversions tend to climb steadily in rankings.

3. Pricing strategy

Price competitiveness is another key A9 factor. Amazon rewards listings that offer good value compared to similar products.

• Products priced too high relative to competitors may rank lower.

• Promotions, coupons, and discounts can improve visibility temporarily by increasing conversion rates.

• Keeping prices stable helps maintain sales velocity, avoiding ranking drops caused by sudden fluctuations.

4. Availability and fulfilment

Inventory management affects both customer experience and ranking. A product that’s frequently out of stock loses sales momentum, which harms its performance metrics.

Fulfilment method also matters. Listings using Fulfilment by Amazon (FBA) tend to rank higher because they qualify for Prime delivery and faster shipping. This directly improves conversion rates and customer satisfaction, two metrics Amazon values highly.

5. Customer reviews and ratings

Reviews are one of the most powerful ranking signals. Products with a higher number of positive reviews have better click-through and conversion rates, creating a feedback loop that reinforces ranking strength.

• Maintain a rating of 4 stars or higher for strong credibility.

• Respond to negative feedback professionally to show reliability.

• Use follow-up emails or packaging inserts (compliant with Amazon’s policies) to encourage honest reviews.

6. Images and content quality

A9 also evaluates engagement metrics such as time spent on the product page. High-quality images and clear copy reduce bounce rates and increase conversions.

• Use high-resolution photos that show multiple angles and product details.

• Include lifestyle imagery where relevant.

• Write descriptions that focus on benefits and address customer concerns directly.

7. Delivery performance and return rates

Amazon monitors how quickly products are delivered and how often customers return them. Fast, reliable shipping improves customer satisfaction and supports higher rankings. Conversely, high return rates or order defects signal poor product quality or misleading listings, which can damage visibility.

The importance of conversion rate to A9

The single most influential metric in A9 is conversion rate. Every part of your listing, from title to images, affects how many visitors make a purchase. When conversions rise, Amazon interprets it as a positive user experience and rewards you with better ranking.

Optimising for conversion means:

• Writing persuasive copy that communicates value.

• Ensuring competitive pricing and availability.

• Providing clear, trust-building information such as guarantees or delivery times.

The more customers who complete purchases after viewing your page, the more likely Amazon is to feature your product prominently.

The role of advertising in ranking

While A9 focuses on organic rankings, paid advertising (Amazon PPC) can indirectly boost performance. Sponsored listings increase exposure, which can lead to more clicks and sales. The algorithm then recognises these conversions and may improve organic placement over time.

However, advertising alone won’t sustain rankings if conversion rates or reviews are poor. Long-term success requires balancing paid visibility with organic performance optimisation.

How to optimise for the A9 algorithm

To improve your product rankings and visibility, focus on the following strategies:

1. Keyword optimisation – Research high-intent search terms using tools like Helium 10 or Semrush, and include them naturally throughout your listings.

2. Improve product titles – Use a clear, keyword-rich structure that highlights brand, model, key features, and size.

3. Enhance images – Include at least seven images per product, with clear focus and good lighting.

4. Write persuasive bullet points – Address common customer questions and highlight product benefits.

5. Maintain stock levels – Avoid running out of stock by forecasting demand and setting reorder alerts.

6. Use FBA if possible – This improves delivery speed and buyer confidence.

7. Encourage reviews ethically – Provide excellent service and follow Amazon’s communication guidelines.

8. Monitor analytics – Track conversion rates, impressions, and keyword performance through Amazon Seller Central.

These actions help you align with Amazon’s algorithmic preferences while building trust with customers.

Challenges sellers face with A9

Many sellers underestimate how dynamic Amazon’s ranking system is. The A9 algorithm updates frequently to prevent manipulation and improve relevance. Common challenges include:

• Maintaining consistent sales velocity during competitive seasons.

• Handling sudden ranking drops after algorithm updates.

• Managing negative reviews that affect both sales and ranking.

• Competing with large brands that have significant advertising budgets.

To overcome these, focus on customer satisfaction and long-term performance rather than short-term ranking tactics.

The future of Amazon search ranking

Amazon’s algorithm continues to evolve, increasingly incorporating artificial intelligence and buyer behaviour analytics. Future updates are likely to place even greater emphasis on personalisation, voice search, and post-purchase satisfaction metrics. Sellers who invest in understanding customer intent and delivering consistently high-quality experiences will remain competitive.

Conclusion

The Amazon A9 algorithm is built to prioritise products that generate sales, delight customers, and provide reliable value. To succeed, sellers must combine technical optimisation with outstanding service and consistent delivery. By improving keyword relevance, conversion rates, and product quality, you can work with A9’s logic rather than against it, ensuring long-term visibility and profitability on the platform.

We have also written in depth articles on Why Sell on Amazon and How the Amazon A9 algorithm ranks products as well as our Amazon Hub to give you further guidance.