What Is the Amazon A9 Algorithm?
Amazon A9 is the name of the original search and ranking engine Amazon built to decide which products appear, and in what order, for a given shopper search. A9 ranks listings primarily on keyword relevance, sales velocity, conversion rate, and pricing competitiveness — the more a product sold and the more closely its listing text matched a search term, the higher it tended to rank.
For the full mechanics of A9 — how it scores keyword relevance, indexes backend search terms, and weighs historical sales — see our Amazon A9 Algorithm explainer.
What Is “A10”? An Important Caveat
Amazon has never officially confirmed an algorithm called “A10.” It’s a term the seller community adopted to describe how ranking behavior has visibly shifted since roughly 2020 — away from pure sales-velocity and keyword matching, toward signals that reflect genuine customer satisfaction. Treat “A10” as shorthand for current ranking behavior, not a publicly documented Amazon system, and be skeptical of any source that states its ranking factors as verified fact rather than seller-observed pattern.
A9 vs A10: Key Differences
| Factor | A9 Era (pre-2020) | A10-Era Behavior (2026) |
| Primary driver | Sales velocity + keyword match | Conversion rate + relevance + trust signals |
| Role of PPC | Strong organic lift from ad spend alone | Ads aid visibility; less direct organic lift than before |
| External traffic | Largely ignored | Traffic from Google, social, and influencers appears to be rewarded |
| Seller reputation | Minor factor | Feedback score, order defect rate, and return rate carry more weight |
| Review quality | Volume mattered most | Volume plus authenticity and recency both matter |
| Keyword strategy | Dense keyword stuffing worked | Natural, relevance-matched keyword placement performs better |
Amazon Ranking Factors in 2026
Based on current seller-community analysis and observed ranking behavior, these are the factors most consistently reported as influential:
Conversion Rate
Widely reported as the single most influential factor — the percentage of shoppers who buy after clicking through to a listing.
Click-Through Rate (CTR)
How often a listing gets clicked when shown in search results — driven mainly by main image, price, and review count/rating at a glance.
External Traffic Quality
Traffic driven to a listing from outside Amazon — Google, social platforms, influencer content — appears to carry more organic weight than it did under A9.
Seller Authority & Reputation
Feedback score, order defect rate (ODR), and fulfillment reliability now factor into visibility, not just the individual listing’s own metrics.
Reviews, Ratings & Return Rate
Rating quality, review recency, and — increasingly — return rate all signal whether a listing is delivering on what it promises.
Relevance & Keyword Placement
Still foundational — Amazon needs to understand what a product is before any other factor matters — but natural placement across title, bullets, and backend terms now outperforms dense keyword stuffing.
How to Optimize for A9 and A10 Together
- Don’t abandon keyword fundamentals: relevance is still the entry ticket — A10-era factors decide rank among listings that already match the search intent.
- Treat PPC as a launch lever, not a permanent crutch: use ads to generate initial velocity and reviews, then let organic conversion carry more of the weight over time.
- Invest in off-Amazon traffic: even modest, consistent traffic from Google, social, or an email list appears to help more under current ranking behavior than it did historically.
- Protect account health metrics: ODR, late shipment rate, and valid tracking rate are no longer just compliance boxes — they plausibly influence visibility.
- Prioritize genuine reviews over volume alone: use Amazon’s built-in Request a Review tool rather than incentivized or manufactured review tactics, which carry real account risk.
These principles connect directly to listing quality — see our Amazon Listing Optimization Service for how we apply them for clients.
A 90-Day Action Plan
| Phase | Timeframe | Focus |
| Foundation | Days 1-30 | Keyword audit, listing relevance check, image/price CTR review, account health check |
| Momentum | Days 31-60 | Launch or refine PPC for velocity, begin review-generation cadence, test one external-traffic channel |
| Compounding | Days 61-90 | Scale what’s converting, monitor organic rank movement against PPC spend, formalize an off-Amazon traffic routine |
A9/A10 Considerations for UK vs US Sellers
Ranking behavior appears consistent in principle across Amazon.co.uk and Amazon.com, but the practical inputs differ: UK review velocity is typically slower given a smaller shopper base per category, and UK PPC costs are often lower — meaning UK sellers may need a longer runway to build the review and conversion signals that carry weight under current ranking behavior. Cross-market sellers should track rank movement separately by marketplace rather than assuming a change on one storefront will mirror the other.
Frequently Asked Questions
Q: Is A10 an official Amazon algorithm?
A: No. Amazon has not publicly confirmed an algorithm called “A10.” It’s a seller-community term describing observed shifts in ranking behavior since around 2020.
Q: What is the biggest difference between A9 and A10?
A: A9 rewarded sales velocity and keyword matching most heavily. Current ranking behavior weighs conversion rate, external traffic, and seller reputation more heavily alongside relevance.
Q: Does PPC still help my organic ranking?
A: Yes, but less directly than before — ads are best used to generate initial sales velocity and reviews, with organic conversion and relevance carrying more long-term weight.
Q: Does external traffic from Google or social media actually affect Amazon rank?
A: Seller-reported data and industry analysis consistently point to a positive effect, though Amazon hasn’t published the exact mechanism or weighting.
Q: How long does it take to see a ranking change after optimizing a listing?
A: Typically several weeks — Amazon needs enough sales and engagement data at the new baseline before rank meaningfully shifts, which is why the 90-day plan above is structured in phases rather than expecting immediate movement.
Q: Should UK and US listings use the same keyword and ranking strategy?
A: The underlying principles are the same, but review velocity and PPC costs differ enough between marketplaces that rank progress should be tracked and benchmarked separately for each.
