Amazon SEO: How the A9 Algorithm Works
How Amazon's Search Algorithm Differs From Google
Amazon and Google solve fundamentally different problems. Google helps people find information. Amazon helps people buy products. This difference shapes every aspect of their respective algorithms. Google evaluates content quality, backlink authority, user engagement signals, and hundreds of other factors to rank web pages. Amazon evaluates whether showing your product for a given search term will result in a sale, which generates revenue for Amazon. Every ranking decision Amazon makes is ultimately a revenue optimization decision.
This means Amazon's algorithm heavily favors products that sell. A product that converts 15% of visitors into buyers will outrank a product that converts 8%, all else being equal, because Amazon earns more revenue per impression from the higher-converting product. This performance-based ranking creates a virtuous cycle: products that rank higher get more traffic, which generates more sales, which reinforces their ranking. Breaking into this cycle as a new product requires strategic use of PPC advertising to generate the initial sales velocity that the algorithm needs to see.
The Primary Ranking Factors
Keyword Relevance
Amazon can only show your product for a search term if your listing contains that term somewhere in its indexed text: title, bullet points, description, backend keywords, or brand name. If a customer searches "stainless steel water bottle" and those words do not appear anywhere in your listing, Amazon will not display your product regardless of how relevant it actually is. Thorough keyword research and strategic keyword placement in your listing are the foundation of Amazon SEO. Without relevance, no other optimization matters.
Title keywords carry more weight than keywords in other listing fields. A keyword in your title tells Amazon that your product is primarily about that term. The same keyword in a bullet point indicates secondary relevance. Backend keywords indicate tertiary relevance. This hierarchy means your most important, highest-volume keywords must be in your title, with supporting keywords distributed across bullets and backend fields.
Sales Velocity
Sales velocity measures how many units your product sells in a given time period relative to other products in the same category. It is the single most important performance signal for Amazon's algorithm. A product generating 50 sales per day on the keyword "yoga mat" will rank higher than a product generating 10 sales per day on the same keyword. Amazon weights recent sales more heavily than older sales, which is why new product launches require aggressive advertising to generate the initial velocity needed to establish organic ranking.
Sales velocity also explains why stock-outs are so damaging. When you run out of inventory, your sales velocity drops to zero. Your organic ranking deteriorates rapidly, often losing weeks or months of ranking gains within days. When inventory returns, you are essentially relaunching the product, needing PPC to rebuild the velocity that your stockout destroyed. Consistent inventory management is therefore an SEO strategy as much as it is an operational one.
Conversion Rate
Conversion rate is the percentage of people who visit your listing and then purchase your product. Amazon tracks this metric per keyword, meaning your product might convert at 18% for "silicone spatula set" but only 6% for "kitchen utensils." The algorithm uses these per-keyword conversion rates to determine ranking. If your listing converts poorly for a specific keyword, Amazon will reduce your visibility for that term even if you are generating good sales through other keywords.
Improving conversion rate requires optimizing every element that influences the purchase decision: product images (professional lifestyle and infographic photos), pricing (competitive within the niche), reviews (quantity and rating), bullet points (addressing customer concerns and objections), and A+ Content (visual storytelling for Brand Registry sellers). Each element contributes to the customer's confidence that your product is the right choice, which translates directly into conversion rate and therefore ranking.
Reviews and Ratings
While Amazon has never confirmed that reviews directly influence search ranking, the correlation is strong and well-documented by seller communities. Products with more reviews and higher average ratings consistently rank higher than similar products with fewer or lower-rated reviews. The likely mechanism is that reviews influence conversion rate (customers are more likely to buy products with many positive reviews), and conversion rate directly influences ranking. In this view, reviews are an indirect ranking factor that works through conversion rate.
Generating reviews ethically requires patience. Amazon's terms of service prohibit incentivized reviews, paid reviews, and review manipulation. Legitimate strategies include Amazon Vine (for Brand Registry sellers, lets you give away up to 30 units to verified reviewers), the "Request a Review" button in Seller Central, product insert cards that ask for feedback (without offering incentives), and exceptional product quality and customer service that naturally inspire customers to leave positive feedback. Our review strategy guide covers the approved methods in detail.
Factors That Hurt Your Ranking
High return rates signal to Amazon that your product does not meet customer expectations. Products with return rates significantly above the category average may see ranking suppression. Monitor your return reports in Seller Central, read every return reason, and address product quality or listing accuracy issues that cause returns. If customers return your product because it is "smaller than expected," add size comparison images to your listing. If returns cite quality issues, work with your supplier to improve manufacturing standards.
Pricing yourself significantly above competitors for an equivalent product reduces conversion rate, which reduces ranking. Amazon shoppers compare prices across listings, and a 20% premium over similar products requires a clear justification (more reviews, better images, additional included items) or your conversion rate will suffer. Conversely, pricing too low can hurt perceived quality and may also reduce total revenue, which Amazon also considers.
Listing suppression occurs when Amazon detects policy violations, missing required information, or content that violates their guidelines. Suppressed listings are invisible in search results until the issue is resolved. Common triggers include missing or incorrect product category assignment, claims that violate advertising standards (medical claims, unsubstantiated "best" claims), missing required product information (weight, dimensions, material), and image violations (text on the main image, non-white background). Check your account health dashboard regularly for suppressed listing alerts.
The Flywheel: How Ranking Compounds Over Time
Amazon SEO operates as a flywheel. PPC advertising generates initial sales, which builds sales velocity, which improves organic ranking, which generates organic (free) sales, which further improves velocity and ranking, which generates even more organic sales. Each rotation of the flywheel reduces your dependence on advertising. A product that generates 30% of its sales from organic traffic in month 1 might generate 60% organically by month 6 as the flywheel builds momentum.
Track your organic sales percentage over time using your TACoS (Total Advertising Cost of Sale) metric. If TACoS is decreasing while total revenue is stable or growing, your organic rankings are improving. If TACoS is increasing, your organic rankings may be declining, requiring investigation. The goal for a mature product is TACoS below 10%, meaning advertising costs are a small fraction of total revenue because organic sales carry most of the volume.