How does Amazon's ranking algorithm actually work?

What is the A9 algorithm, and what is A10?

A9 is the name of the search system Amazon built for product search, named after the subsidiary that developed it. "A10" is not an official Amazon term. It is shorthand the seller community adopted to describe the observation that Amazon's ranking has shifted over time toward external traffic, organic sales and seller authority, and away from pure keyword matching and paid velocity.

Amazon does not publish the algorithm and has never confirmed an "A10". Treat both names as labels for the same thing: a system that tries to put the product most likely to sell at the top of the page.

Which ranking factors actually matter?

They divide cleanly into two groups: whether you are eligible to rank for a term at all, and how well you perform once you are.

Relevance gets you into the auction. Performance decides where you finish. Most sellers work exclusively on the first and wonder why position does not move.

Why does conversion rate matter more than keywords?

Because Amazon is paid on sales. A listing that converts at 18% earns Amazon more per impression than one converting at 6%, so the system has a direct commercial reason to show it more often.

This is the part that surprises people arriving from Google SEO. You can be perfectly indexed for a term and still sink, because every impression Amazon gives you is being measured. Ranking is not awarded and then held; it is continuously re-earned.

The practical consequence: if your conversion rate is below your category norm, keyword work is the wrong first job. Fix the images, the price position and the first bullet, then chase rank. We set out the order in how to optimise an Amazon listing.

What does not affect Amazon ranking?

Four things sold as ranking services do nothing on Amazon:

• Backlinks and domain authority. There is no link graph inside Amazon search. Anyone selling DA or DR packages for Amazon rank is selling a Google product for an Amazon problem.
• Keyword density and repetition. Amazon indexes a term once. Repeating it in the title, the bullets and the backend field wastes the backend field.
• Meta descriptions and page titles in the Google sense. Your listing has no meta description.
• Sales velocity you did not earn. Manipulated velocity is detected and reversed, and the account is at risk under Amazon's Community Guidelines.

External traffic does have some effect, but as a source of real sales rather than as a signal in itself.

One eligibility point is worth separating from the rest, because it is often mistaken for a ranking factor: Brand Registry does not rank you higher. What it does is unlock A+ Content, Sponsored Brands and Vine — all of which act on conversion rate and sales velocity, which are ranking factors. The lift is real; it simply arrives through performance rather than through any status Amazon assigns your brand.

How do you check whether you are indexed for a keyword?

The reliable manual method takes about a minute per term:

1. Search Amazon for your exact keyword plus your ASIN, separated by a space.
2. If your listing appears, you are indexed for that term.
3. If nothing appears, you are not — and no amount of bidding will produce organic rank for it.

Indexing usually follows a listing change within 48 hours to two weeks. Rank movement takes longer, because it depends on conversion and sales history accumulating behind the new terms.

Our keyword mapper will show you which of your terms are competing with each other across fields, which is the most common cause of a term never indexing at all.

How does the Buy Box affect ranking?

Losing the Buy Box effectively removes you from organic ranking, because a listing without it has no “Add to Basket” button to convert against. Rank is earned through conversion, so a listing that cannot be bought in one click stops earning it.

The Buy Box is awarded per offer, not per listing, and the inputs are largely operational rather than editorial:

• Landed price. Item price plus delivery, compared against other offers on the same ASIN.
• Fulfilment method and speed. FBA and Prime-eligible offers are advantaged on delivery promise.
• Stock. An out-of-stock offer cannot hold the Buy Box, and rank decays while you are away.
• Seller performance. Late dispatch, defect rate and cancellation rate all feed in.

Two practical consequences follow. First, a stock-out is a ranking event, not just a sales event — the position you regain after a fortnight out of stock is usually below the one you left. Second, if you sell on a shared ASIN, a competitor undercutting you on landed price takes both the sale and, over time, the organic position. Amazon calls it the Featured Offer in its own documentation; the qualifying conditions are set out in Seller Central under Featured Offer eligibility, and they are worth reading in the version current for your account rather than a third-party summary.

Check the Buy Box percentage in your business reports before you diagnose a rank drop as a keyword problem. If it fell first, the ranking did not cause the sales drop — the lost Buy Box caused both.

How long does it take to move Amazon rank?

Three separate clocks run, and conflating them is why sellers panic in week two.

Anyone promising ranked keywords in days is describing manipulation rather than optimisation.

Your rank dropped — how do you find out why?

Work through the eligibility questions before the optimisation ones. Most sudden rank drops are caused by something that removed the listing from competition, not by a competitor out-optimising you overnight.

In order, because each step is cheaper than the one after it:

1. Is the listing live and unsuppressed? A missing required attribute takes an ASIN out of search without taking it off the site. There is a full account of this in why Amazon suppresses a listing.
2. Did you go out of stock? Check the date against the drop. Rank decays during a stock-out and returns lower than it left.
3. Did you lose the Buy Box? Compare Buy Box percentage week on week in your business reports.
4. Did the price move? Yours or a competitor's. Conversion rate follows price position closely, and rank follows conversion.
5. Did conversion fall without a price change? Look for a new review below three stars, a changed main image, or a competitor's new A+ Content.
6. Only then, is it indexing? Re-run the ASIN-plus-keyword check above on your priority terms, and cross-check the search term report in Amazon Ads to see whether the term still triggers your listing at all.

Log the date of every listing change you make. Without a change log you cannot tell a rank drop caused by your own edit from one caused by the market, and the two need opposite responses. Our listing checker will flag the eligibility problems in the first three steps, and the Amazon SEO service page sets out how we run the same sequence on a client account.

One caution on tooling: third-party rank trackers sample a keyword from one location at one moment, so small daily movements are usually noise. Compare weekly averages, not daily positions.

Questions people also ask

Last reviewed 1 August 2026. We update articles in place rather than republishing at a new URL, so the link you have keeps working.