How Does Amazon’s A9 Algorithm Work?
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What is Amazon A9 Algorithm?

The Amazon A9 algorithm is the algorithm that powers Amazon’s search engine. It allows Amazon to best match the customer searches to the customer’s desire product. It is one aspect, amongst many, that Amazon sellers would need to be aware of to become a successful seller.

What makes Amazon A9 algorithm unique is its emphasis on conversion or “purchases” that the customer has made. For example, if all things are equal on the search term “Garlic Press,” product A gets 40 conversions on this search term, while product B gets 30 conversions, product A should rank relatively higher than product B.

On the other hand, the Google search engine uses factors other than conversions. It uses the relevancy of the content measured by “bounce rates”. This reflects the nature of the two – Amazon is an E-Commerce “buying” website, and Google is a content discovery site. The key goal of Amazon is for the end customer to come out with a purchase of the product they are looking for. On Google, the goal is to have the user discover the right content.

Key Factors that Drives Amazon A9 Algorithm

Although Amazon has never stated the exact logic of the A9 algorithm. Based on my experience and other sellers we can deduce the key factors that drive ranking on A9.

Sales Velocity

The sales momentum of your ASIN, based on a moving average of a date range. This date range is highly speculative, but it is estimated to be around 30 days. That is why a lot of questions about ranking and sales momentum from the Amazon seller community. Also why it is hugely important to stay in stock.


There is a noticeable rank or algorithm boost due to the number of customer reviews you have on your ASIN. Although, there is a diminishing return as more reviews you collect. There is a bigger rank difference between a product with 0 vs. 100 reviews than 1000 vs. 2000 reviews. There are soon automation tools out there, such as FeedbackFive, that can automate the process of after-sales service on Amazon that can potentially up your review count.

Fulfillment Method

Amazon will give preference to products that are Fulfilled by Amazon (FBA) than not. This is centered around customer satisfaction, as FBA products are eligible for 1-2 days prime shipping. If you want to succeed in the Amazon game with a competition using FBA, enrolling in FBA is a must.

Amazon PPC

Using Amazon advertising and bidding on specific keywords, the A9 algorithm will give some organic rank to keywords that convert in a sale even if it is discovered by Sponsored Products. We have a comprehensive article on how organic rank can be achieved by just Amazon PPC here.

Off-Amazon Traffic

Driving quality traffic from Google and other social media such as Facebook will boost the A9 algorithm as well. Amazon indirectly has shown it has placed importance on off Amazon traffic by introducing Amazon Attribution.

Listing Optimisation

Having your listing optimized with relevant keywords placed in the right fields and with the right photography. Much more on listing optimization later.

Positive Feedback Loop “Flywheel Effect”

A lot of sellers are looking for that one tactic to be successful on Amazon. This pandemic of finding that one “magic pill” is exacerbated by Amazon gurus, influencers, and service providers looking to give the audience what they want.

Unfortunately, the truth is there not one tactic that allows you to be successful on Amazon for the long term. What needs to happen is that multiple positive effects need to work together. This in turn creates a positive feedback loop. This positive feedback loop allows the Amazon A9 Algorithm to get a full picture of whether your ASIN is really giving the customer what they want. Amazon has a term for this, and it is called the “Flywheel Effect.”

If the above steps on the flywheel do not work together in tandem, the positive feedback loop will stop. For example, if you concentrate on a tactic that gets you more clicks, but your conversion rate is bad relative to the competition, theA9 algorithm will not give you a net positive rank relative to your competition even though you have driven more clicks to your listing.

Keyword Research

It is very important to make sure that your product listing gets a positive impression from the Amazon A9 algorithm. You can do this by making sure you are using relevant keywords. Having relevant keywords in your product listing key areas such as title and bullet tells the A9 algorithm what exactly your product is. It’s also on your way to starting initiating the flywheel effect via impression given by your keywords.

Tools, such as Jungle Scout’s Keyword Tool allow you to perform keyword analysis on your competition, through a process called reverse ASIN. So what is reverse ASIN? It is a keyword gathering process where the software tool can take an ASIN and show keywords that customers used to search and purchase for that ASIN in the past.

Keyword Relevance

After you acquire a list of keywords via the reverse ASIN process, select a set of highly relevant keywords. You have to make sure that you eliminate the keywords that are relatively less relevant to each other. This step is not an exact science. This step is advantageous to native speakers of the marketplace they are selling for. It gives them an advantage over the Chinese sellers selling on these marketplaces.

You want a list of, at most, 30 keywords that are at least 80% relevant to the product. In other words, your ASIN should at least be 80% match with the keyword. What I am explaining to you is very subjective based on what you define as relevant. The number of actual keywords you can get in your reverse ASIN, or your product’s uniqueness.

How do you know a keyword is % relevant. The below example can be a broad guide for you to follow. If your product is a Yoga Wheel that is 10 inches in diameter in size, the following would be its keyword and related relevancy:

One quick and easy way to figure out relevancy is to do a search on Amazon using that keyword. See if the exact similar product is amongst both the Sponsored Ads and the first 5-6 organic results.

How to Optimize your product listing for Amazon A9 Algorithm?

The first step and probably the most important step is to have your product listing optimized. Time spent on optimizing product listings is time well spent. It will give you the most leverage on your listings. Having your product listing converting at 15% versus 20% is a huge difference. It will lower your cost per sale and hence increase your sales and profit materially.

We have written a very comprehensive guide on the topic of Amazon listing optimization. But we will also give a brief overview.


Titles should be within the 200 character limit, do not repeat words. Make sure to use one main keyword phrase at the beginning of the title. Then add information about the variation (size, color, model) right after. A good title format should look like the below.

{main keyword 1} – {variation} – {words in search term the describes product 1} – {words in search term the describes product 2….} – if it is an accessory to a main product add: “for {main product} – by {Brand}

Bullet Points

5 bullet points that can further expand on the benefits of the product. Try to speak to the audience. Add keywords into the bullet point if it makes sense. Make sure it makes grammatical sense when incorporating the keywords.

Product Description

The product description affects the A9 relatively less than the bullet points and titles. Feel free to describe and let the reader envision how using the product can relieve their pain point. Clarify potential questions about your product, such as is there a product warranty? what does the package include? Is anything the customer might need sold separately?

Backend Search Terms

The backend search terms are on the backend of the listing and are not customer-facing. It is one of the data points picked up by the A9 algorithm is used to match customer searches. You will fill in the backend search term field within 249 bytes limit restrictions, excluding spaces or punctuation such as a comma. Below are some of the best practices for providing search terms:

  • Don’t include product identifiers such as brand names, product names, compatible product names, ASINs, UPC codes, etc.
  • Don’t provide inaccurate, misleading, or irrelevant information like the wrong product category, the wrong gender, out-of-context words, etc.
  • Avoid excessively long content. Respect the limits that are set for different fields.
  • Don’t provide redundant information already captured in other fields such as title, author, brand, etc. It won’t improve your product placement in shopping results.
  • When entering several words as a search term, put them in the most logical order. A customer is more likely to search for “big stuffed teddy bears” than for “teddy stuffed bears.”
  • Use a single space to separate keywords. No commas, semicolons, or carets are required.
  • Don’t include statements that are only temporarily true, such as, “new,” “on sale,” or “available now”
  • Avoid including subjective claims such as amazing, good quality, and so on, since most customers don’t use subjective terms in their queries
  • Don’t include common misspellings of the product name – our systems compensate for common customer misspellings and also offer corrective suggestions.
  • Don’t provide variants of spacing, punctuation, capitalization, and pluralization (“80GB” and “80 GB,” “computer” and “computers,” etc.) Our systems automatically include different case forms, word forms, and spelling variants for searching.
  • Don’t include terms that are abusive or offensive in nature.
  • Abbreviations, alternate names, topics, and key characters (for books, movies, etc) can be included as search terms.

Optimise Images

Make sure your main image is of high quality, very clear, and crisp with white background. Make sure your product takes up as much white in the background as possible, as you can make an impression on the thumbnail of the search results. Other photos you should have are product call out, instructional photos, and lifestyle photos.

Use Amazon Advertising to further Optimize

The Amazon in-platform paid advertising has a direct effect on the organic ranking of the product. This paid-to-organic traffic relationship is very different than other platforms. For example, on Google ads, if the customer searches and clicks on your Google ads, there is no direct effect on the organic ranking of that keyword.

On Amazon, the story is different. The factors that help influence Amazon’s organic ranking also influence Amazon’s paid search ranking. Meaning the goal of Amazon’s organic ranking algorithm is to serve products that are high on relevance and in buyability. You can read more detail on how Amazon PPC can influence Amazon’s organic ranking.

Another way to use Amazon PPC is to improve the optimization of your product listing by looking at the converting search terms’ metrics. The true litmus test on keyword relevancy is sales. With Amazon PPC, you can attribute keywords to their sale, giving a true read on the keywords’ relevancy.

So regularly look into your Amazon PPC campaigns’ reports, make sure that your listing has those keywords that have attributed to a sale. Continue to iterate this process to make sure your listing is as optimal as possible with the strongest keywords.

How SellerMetrics can help your listing optimize further for A9

As mentioned above, to get a stronger read on the relevancy of your keywords, you should regularly look into your Amazon PPC metrics. Ensuring you are 1) driving traffic from relevant keywords and 2) having these relevant keywords in your product listing will be very conducive to the Amazon A9 algorithm.

Our Amazon PPC Software, SellerMetrics, has an analytics feature that will allow you to see Search Terms and Keyword with their related metrics performance with just a few clicks of a button. You will no longer need to be running and downloading multiple reports and between multiple accounts on the Amazon advertising interface.

Use this feature to analyze your search term and keyword data by date range, then filter out your metrics (ACoS %, Orders, Sales etc) further by using the filtering dropdown.

The sort your filter Search Term/Keywords data by its orders/sales to find the top performers.

Our product’s beauty is our unified accounts feature, which consolidates all your Amazon accounts data into one screen. This unique feature, not offered by any of our competitors, will save time and optimize your analysis workflows. This is an amazing feature to have if you manage multiple accounts, such as Amazon PPC agencies.

If you have questions or insights to share, please feel free to post them via the comments section. Please also consider joining our Facebook Group where we discuss any questions you may have about running an Amazon business.

We are SellerMetrics, our Amazon PPC tool helps Amazon sellers, brands, KDP Authors and agencies navigate Amazon Advertising PPC via bid automation, manual bid changes, and analytics.


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