2024-11-05 · 12 min read
The Amazon A9 Algorithm Explained for Sellers
How Amazon ranks products in search results, what factors matter most, and how to optimize your listing to rank higher.
Amazon's search algorithm (commonly called A9, though Amazon now refers to it as A10) determines which products appear first when a customer searches. Understanding how it works is the foundation of Amazon SEO.
The core principle: Amazon ranks products that sell
Amazon makes money when customers buy. So the algorithm ranks products that are most likely to result in a purchase. This means conversion rate, sales velocity, and customer satisfaction signals carry more weight than any keyword trick.
A new listing with excellent reviews, strong conversion rate, and consistent daily sales will outrank an older listing with more backend keywords but poor performance metrics.
Relevance signals
Before Amazon considers performance, it filters for relevant results. Your listing must contain the customer's search term somewhere — in the title, bullets, description, or backend keywords — to appear at all.
Title: Amazon weighs keywords in the title most heavily. Put your primary keyword within the first 80 characters (what shows in mobile search results). Include your brand name, the product type, and 1-2 key attributes (size, color, material, count).
Bullet points: Use your top 3-5 secondary keywords naturally in bullets. Each bullet should highlight one benefit, not just a feature.
Backend search terms: Use the 250 characters in Seller Central's backend keywords field for synonyms, alternate spellings, and terms that do not fit in the listing copy. Do not repeat terms already in your title.
Performance signals
Click-through rate (CTR): How often searchers click your listing versus others shown on the same results page. Better images, a more compelling title, and a strong review count improve CTR.
Conversion rate: The percentage of people who click your listing and buy. Better images, clearer description, and social proof (reviews) drive conversion.
Sales velocity: How many units you sell per day. Higher velocity = higher ranking. This is why new product launches use promotions and PPC to build initial velocity.
Reviews and ratings
A 4.5+ average rating with 50+ reviews significantly outperforms a listing with fewer reviews, even if the product is identical. Ratings affect both CTR (buyers see stars in search results) and conversion rate.
Optimizing for A9
Run PPC ads for your target keywords. Ad clicks generate sales, and those sales improve your organic ranking for those keywords. This is the fastest way to rank a new listing.
Monitor your listing's click-through rate in Brand Analytics. If CTR is below 0.5%, test a new main image. If conversion rate is below 10%, work on your bullet points and additional images.
Keep your inventory in stock. Going out of stock resets your ranking momentum and can take weeks to recover.