UNDISCLOSED

Amazon Ranking Intelligence

Amazon Ranking Algorithm —
Hidden Factors A9 Measures But Never Documents

A9 processes 100+ ranking signals. Amazon officially documents 3 of them. The rest are never published.

Keywords, price, and reviews are table stakes — every serious seller is optimising for these. The sellers consistently ranking on page one are managing seven behavioral signals that Amazon's A9 algorithm measures in real time and never officially discloses.

June 2026

12 min read

Ranking & SEO

Chintan K C

A9 does not rank listings. It ranks purchase probability. The factors that determine that probability are almost entirely behavioral — not textual. And Amazon does not tell you which ones they are.

Amazon's Official Guidance

Keyword optimization

Competitive pricing

Positive review count

A+ Content and images

Why this matters

Two listings with identical keywords and pricing can rank 40 positions apart — because one seller is managing behavioral signals and the other is not. This post covers all seven, where to find them in Seller Central, and what to fix first.

Quick Reference

All 7 Hidden Ranking Factors — At a Glance

Each of these signals is measurable in Seller Central right now. What makes them "hidden" is not that the data is inaccessible — it is that Amazon never tells you these are the signals A9 is using to determine rank. Here is every factor, where to find it, and the benchmark that separates healthy from critical.

Behavioral, Not Textual

A9 ranks purchase probability — driven by what customers do, not what your listing says.

Rolling Data Windows

A9 evaluates signals continuously — past performance does not guarantee current rank.

PPC Affects Organic

Converting PPC campaigns lift organic rank on the same keywords — the Halo Effect is real and measurable.

Rank Doesn't Self-Restore

A stockout that drops rank requires active rebuilding — it does not recover on its own when restocked.

#	Factor	Where to Check in Seller Central	Healthy Benchmark	Critical Threshold	Impact
F1	Sales Velocity Reports → Business Reports → Sales & Traffic by Date → Units Ordered	Week-over-week Units Ordered trend across 30 days	Rising WoW	Declining 2+ weeks	Highest
F2	Click-Through Rate Brands → Brand Analytics → Search Terms \| Campaign Manager → keyword level	CTR = Clicks ÷ Impressions × 100 on primary keyword	Above 0.6%	Below 0.3%	High
F3	Conversion Rate Reports → Business Reports → Detail Page Sales by ASIN → Unit Session %	Unit Session Percentage — orders divided by page sessions	Above 15%	Below 10%	Highest
F4	PPC Halo Effect Advertising → Campaign Manager → Exact Match campaigns → keyword-level Orders	Organic rank movement alongside Exact Match PPC conversions	Rank rising with PPC	PPC spend, zero CVR	High
F5	Review Velocity & Recency Seller Central → Feedback Manager \| Product Reviews section	New reviews per 30 days + days since last review received	3+ reviews / 30 days	0 reviews / 30 days	Medium
F6	Inventory Availability Inventory → FBA Inventory → Days of Supply column	Days of Supply = current FBA units ÷ daily sales rate	60+ days of supply	Below 30 days	Critical Risk
F7	Listing Completeness Inventory → Manage Inventory → Edit Listing → all attribute fields	Title, bullets, description/A+, backend keywords, product attributes, images	7 / 7 complete	Below 5 / 7	Medium

KPI Benchmark Zones — At a Glance

Green — Healthy

Velocity: Rising WoW

CTR: > 0.6%

CVR: > 15%

Reviews: 3+ / 30 days

Inventory: 60+ days

Completeness: 7 / 7

Yellow — Investigate

Velocity: Flat 14+ days

CTR: 0.4% – 0.6%

CVR: 10% – 15%

Reviews: 1–2 / 30 days

Inventory: 45–60 days

Completeness: 5–6 / 7

Red — Act Immediately

Velocity: Declining 2+ wks

CTR: < 0.3%

CVR: < 10%

Reviews: 0 / 30 days

Inventory: < 30 days

Completeness: < 5 / 7

Deep Dive

The 7 Hidden Factors — Complete Breakdown

Each factor explained with where to find it, what to measure, what healthy looks like, and the exact action to take when it is not. The first two factors are open to all readers. Full access requires a free account.

Factor 1 of 7

Sales Velocity

The most weighted behavioral signal in A9

Free Preview

Reports → Business Reports → Sales and Traffic by Date → Units Ordered

A9 Signal: Sales Velocity

Velocity = Week N Units Ordered vs Week N-1 Units Ordered

WoW Change = ((This Week − Last Week) ÷ Last Week) × 100

Target State: Rising week-on-week across 4+ weeks

Rising WoW — Rank SignalPositive → Rank Reward

Flat 14+ Days — AlertInvestigate immediately

Declining 2+ Weeks — CriticalRank erosion in progress

Velocity is directional momentum — not total units. A product selling 5 units per week rising to 8, then 12, outranks a product selling 20 per week with a flat or declining trend in A9's model.

Factor 2 of 7

Click-Through Rate (CTR)

The first impression signal — before any purchase is possible

Free Preview

Brands → Brand Analytics → Search Terms | Campaign Manager → keyword level CTR

A9 Signal: Click-Through Rate

CTR = Clicks ÷ Impressions × 100

Primary Drivers: Main Image (highest impact) · Title · Price

Healthy: > 0.6% | Average: 0.4–0.6% | Critical: < 0.3%

CTR above 0.6%Image + title resonating

CTR 0.4% – 0.6%Acceptable — monitor and test

CTR below 0.3%Fix main image — A/B test now

Low CTR tells A9 that this listing is not relevant to this search. The algorithm reduces organic impressions — rank drops before you have a chance to convert anyone. Fix CTR before addressing conversion.

Intelligence Access Required

Factors 3–7 + Priority Framework + AI Prompts

Create a free SelluxPro account to unlock the full breakdown — Conversion Rate, PPC Halo Effect, Review Velocity, Inventory Scoring, Listing Completeness, and the complete AI Prompt Library with copy-paste prompts for every factor.

Factor 3: Conversion Rate — Unit Session % diagnosis framework
Factor 4: PPC Halo Effect — how paid campaigns lift organic rank
Factor 5: Review Velocity and Recency — the freshness signal
Factor 6: Inventory Availability Score — rank protection rules
Factor 7: Listing Completeness Index — the tiebreaker
5-step priority framework — what to fix first and why
AI Prompt Library — all 7 factors with copy-paste prompts

Factor 3 of 7

Conversion Rate (Unit Session %)

Members Only

Factor 4 of 7

PPC Halo Effect

Members Only

Factors 5–7 + AI Library

Review Velocity · Inventory · Completeness

Members Only

Factor 1 of 7

Sales Velocity

Most weighted behavioral signal in A9

Behavioral

Reports → Business Reports → Sales and Traffic by Date → Units Ordered

WoW Change = ((This Week Units − Last Week Units) ÷ Last Week Units) × 100

Target: Rising WoW for 4+ consecutive weeks

Rising WoWA9 rewards with rank increase

Flat 14+ daysInvestigate — rank erosion risk

Declining 2+ weeksImmediate action — diagnose root cause

Velocity is directional momentum, not total volume. Rising from 5 to 8 to 12 units per week outranks a stable 20 units per week in A9's purchase probability model.

Factor 2 of 7

Click-Through Rate (CTR)

First-impression signal — decides if a sale is even possible

Visibility

Brands → Brand Analytics → Search Terms | Campaign Manager → keyword level

CTR = Clicks ÷ Impressions × 100

Drivers: Main Image (highest) · Title · Price

> 0.6% Healthy | 0.4–0.6% Average | < 0.3% Critical

Above 0.6%Image and title resonating

0.4% – 0.6%Acceptable — A/B test image

Below 0.3%Urgent — A/B test main image now

Fix CTR before conversion rate. You cannot convert customers who never clicked. Low CTR means A9 is already reducing your impressions — the rank drop starts here.

Factor 3 of 7

Conversion Rate (Unit Session %)

The closing signal — what A9 learns when customers arrive

Conversion

Reports → Business Reports → Detail Page Sales and Traffic by ASIN → Unit Session Percentage

Unit Session % = Units Ordered ÷ Page Sessions × 100

Primary Drivers: Main image · Price vs Buy Box · Star rating · Bullet clarity · A+

> 15% Healthy | 10–15% Acceptable | < 10% Critical

Above 15%Listing closing well — A9 positive signal

10% – 15%Acceptable — audit image and price next

Below 10%Fix listing before scaling PPC — urgently

Scaling PPC when Unit Session % is below 10% sends A9 a negative conversion signal at amplified scale. Fix the listing first — then increase budget. The sequence is non-negotiable.

Factor 4 of 7

PPC Halo Effect

How converting paid campaigns lift organic rank on the same keywords

PPC × Organic

Advertising → Campaign Manager → Exact Match campaigns → keyword-level Orders and ACoS

Halo Effect: PPC Conversion → A9 records sales velocity + CVR signal → Organic rank improves

Condition: Halo fires ONLY when PPC campaigns convert

Setup: Exact Match campaigns on top 5 priority organic keywords

PPC converting + organic rank risingHalo active — maintain spend

PPC converting, rank flat (under 2 weeks)Halo building — allow time

PPC spend with zero conversionsNo halo — negative signal amplified

Use Exact Match, not Broad Match, for Halo campaigns. Broad Match distributes spend across too many terms and dilutes the keyword-specific signal A9 needs to register the Halo. One term, one campaign, concentrated signal.

Factor 5 of 7

Review Velocity & Recency

Freshness outweighs volume — A9 weights recent reviews more heavily

Social Proof

Orders → Manage Orders → completed order → Request a Review button (Amazon-approved)

Velocity = New reviews received per 30 days

Recency = Days since last review received

200 old reviews < 80 recent reviews in A9's model

3+ reviews / 30 daysHealthy velocity — freshness signal active

1–2 reviews / 30 daysLow velocity — increase Request a Review usage

0 reviews / 30 daysFreshness signal dead — urgent action

Use the Request a Review button for every completed order — this is Amazon's officially approved method. Make it a daily habit for your account manager, not a monthly task.

Factor 6 of 7

Inventory Availability Score

The most immediately destructive factor — a stockout drops rank within 72 hours

Rank Protection

Inventory → FBA Inventory → Days of Supply column for this ASIN

Days of Supply = Current FBA Units ÷ Average Daily Sales Rate (30-day)

> 60 days: Safe | 45–60: Restock Now | < 30: Rank at Risk

Restock trigger: Place order when Days of Supply reaches 45

60+ days of supplySafe zone — no rank risk

45–60 daysPlace restock order now

Below 30 daysRank suppression likely starting

Rank does not self-restore after a stockout. When inventory is replenished, you must rebuild sales velocity and conversion signals from the ground up — often requiring additional PPC spend to recover the organic rank built over months.

Factor 7 of 7

Listing Completeness Index

The tiebreaker factor — decides rank when other signals are equal

Quality Signal

Inventory → Manage Inventory → Edit Listing → all attribute fields and Keywords tab

Completeness Checklist (7 items):

✓ Title: 150–200 chars, keyword in first 5 words

✓ All 5 bullets filled, benefit-led

✓ A+ Content activated (Brand Registry)

✓ Backend keywords: 250 bytes, no duplicates

✓ All required attributes filled (material, size, color, count)

✓ 7 images: main + lifestyle + infographic + size + comparison

✓ Brand Story published (Brand Registry)

7 / 7 completeFull completeness signal — maximum A9 scoring

5–6 / 7Near complete — fix remaining in 48 hours

Below 5 / 7Actively harming rank in competitive categories

Do not skip product attribute fields because they are not customer-facing. Missing material, size, and count fields reduce the completeness score — and in competitive categories, completeness is the tiebreaker A9 uses when behavioral signals are similar across listings.

Priority Framework — What to Fix First

Inventory (Survival)Check Days of Supply first — always. A rank built on empty stock disappears overnight and does not recover without effort.

Sales Velocity + Conversion Rate (Growth Engine)If velocity is declining and conversion is below 10% — fix listing first. Conversions drive velocity. Velocity drives rank.

CTR Fix (Visibility)If CTR is below 0.3% but conversion is OK — the problem is search presentation. A/B test main image via Manage Your Experiments.

PPC Halo Check (Amplifier)Once listing converts at 10%+ — scale Exact Match PPC on priority keywords. Track organic rank movement every 2 weeks.

Reviews + Completeness (Weekly Maintenance)Request a Review for every completed order. Fix any missing listing attributes. These are 20-minute weekly habits, not one-time tasks.

Diagnose immediately — Inventory or Conversion?Pull Days of Supply and Unit Session % first. If Days of Supply is below 30, the stockout is the cause. If Unit Session % is below 10%, the listing is the cause.

Pause PPC scale — do not increase budget during a rank dropScaling spend when conversion is low amplifies the negative signal. Reduce bid on underperforming keywords while diagnosing.

Check competitor velocity on your primary keywordIf a competitor gained velocity while yours declined, they may have taken your rank position. Check Brand Analytics click share changes.

Listing completeness before launch dayComplete all 7 listing items before driving any traffic. An incomplete listing receiving PPC traffic sends a low-quality signal to A9 from day one.

Start PPC at low budget — validate conversion firstRun a small Exact Match campaign on your primary keyword. Confirm Unit Session % reaches 10%+ before scaling budget. This sets the Halo Effect in motion safely.

Inventory buffer from launch dayStart with 60 days of supply in FBA. New launch velocity can spike unexpectedly — a stockout in the first 30 days kills momentum that is difficult to rebuild.

Common Mistakes to Avoid

Scaling PPC when conversion rate is below 10%. This amplifies a negative conversion signal to A9 at scale and accelerates rank decline while burning budget on a broken funnel.

Treating ranking as a one-time optimization. A9 uses rolling behavioral data windows. A listing optimized six months ago that has declining signals today will lose rank regardless of past performance.

Expecting rank to recover automatically after a stockout. A9 does not restore rank when inventory is replenished. You must rebuild velocity and conversion signals from zero — typically with additional PPC spend.

Using Broad Match for Halo Effect campaigns. Broad Match dilutes spend across too many search terms and prevents A9 from registering a strong keyword-specific signal for the Halo Effect to fire.

Treating total review count as a health metric. A9 weights recent reviews more heavily. Two hundred old reviews lose to eighty recent ones in A9's relevance model — recency matters more than volume.

Leaving product attribute fields incomplete. Missing material, size, color, and item count fields reduce the Listing Completeness score — an invisible disadvantage that becomes a tiebreaker loss in competitive categories.

AI Prompt Library — All 7 Factors

Same analysis. Done with AI. Pick a factor, copy the prompt, paste your Seller Central data, and get instant diagnosis in under 3 minutes.

Claude

Paste: Business Reports → Sales and Traffic by Date → last 14 days

I am an Amazon seller. Below is my Sales and Traffic by Date report for the last 14 days. [paste data here] Analyze week-over-week change in Units Ordered and tell me: 1. Is my sales velocity increasing, stable, or declining? 2. What is the percentage change week over week? 3. What is the most likely root cause of any decline? 4. What is the single most important action I should take first?

AI returns: velocity trend, WoW change %, root cause analysis, priority action

Gemini

Paste: Campaign Manager → Search Term Report → last 30 days

Below is my Amazon Search Term Report for the last 30 days. [paste data here] For my primary keyword [keyword]: 1. Calculate CTR = Clicks divided by Impressions multiplied by 100 2. Evaluate against benchmarks: above 0.6% healthy, 0.4–0.6% average, below 0.3% critical 3. What is the single most important action I should take?

AI returns: calculated CTR, benchmark zone, single priority action

Claude

Paste: Unit Session %, title, bullets, price, star rating, images list

I am an Amazon seller. My Unit Session Percentage is [X]%. My listing details: Title: [paste] | Bullets: [paste] | Images: [list] | Price: [X] | Star rating: [X] | A+ Content: [active/not active] Diagnose why my conversion rate may be low. Benchmarks: above 15% healthy, below 10% critical. 1. What is the single weakest element in my listing? 2. What should I fix first to improve conversion rate?

AI returns: weakest listing element identified + single priority fix

Claude

Paste: SP campaign data + keyword organic rank at start and end of month

I am an Amazon PPC manager. Below is my Sponsored Products data for the last 30 days — spend, sales, ACoS — plus my primary keyword's organic rank at start and end of month. [paste data here] Tell me: 1. Is my organic rank improving alongside PPC activity? 2. Is the PPC Halo Effect active for this product? 3. Based on this data, what is my approximate Break-Even ACoS? 4. Should I increase, maintain, or reduce PPC spend right now?

AI returns: Halo Effect status, Break-Even ACoS, spend recommendation

Claude

Paste: last 20 customer reviews with dates and star ratings

Below are my last 20 Amazon customer reviews with dates. [paste here] Tell me: 1. How many reviews were received in the last 30 days? 2. What is the average star rating of the last 10 reviews specifically? 3. Is there a declining trend in recent ratings? 4. What is the most common complaint theme in negative reviews?

AI returns: velocity count, recent rating average, trend direction, top complaint

Gemini

Paste: FBA units available, daily sales rate, supplier lead time

Calculate inventory risk for my Amazon FBA product. Current FBA units available: [X] Daily sales rate (30-day average): [X] units per day Replenishment lead time: [X] weeks 1. How many days of supply do I have remaining? 2. Which zone am I in: safe (60+ days), restock trigger (45–60), warning (30–45), or emergency (below 30)? 3. What is the exact date I should place a purchase order to maintain a 60-day buffer from today?

AI returns: days of supply, zone classification, exact reorder date

ChatGPT

Paste: current title, all 5 bullets, backend keywords, images list

Audit and improve my Amazon listing for completeness. Title: [paste current title] Bullet Points: [paste all 5] Backend Keywords: [paste current backend keywords] Primary Keyword: [keyword] A+ Content: [active / not active] Images available: [list] Tell me: 1. What is missing or incomplete based on Amazon best practices? 2. Rewrite my title to be 150–200 characters with [keyword] in first 5 words 3. Write 250 bytes of backend keywords — no duplicates, no commas, space-separated, starting with [keyword]

AI returns: completeness gaps, rewritten title, 250-byte backend keywords

Key Takeaways

What to Do With This Information

Velocity and Conversion Are Your Primary Levers

Sales Velocity and Conversion Rate carry the most weight in A9's purchase probability calculation. Check Units Ordered WoW in Business Reports and Unit Session % in Detail Page Sales every week without exception. If velocity is declining and conversion is below 10%, fix the listing before touching PPC budget.

PPC and Organic Rank Are Not Separate Systems

Converting Exact Match campaigns on your priority keywords generate sales velocity and conversion signals that A9 records identically to organic sales. This is the PPC Halo Effect — and it is the fastest legitimate method to lift organic rank when your listing converts well. Use Broad Match and you dilute the signal. The keyword specificity matters.

Inventory Is a Ranking Asset, Not Just an Operations Task

A stockout drops rank within 72 hours. Recovery is not automatic — it requires rebuilding velocity signals from zero. The Days of Supply metric in FBA Inventory is your early warning system. Set your restock trigger at 45 days, not 30. The cost of holding extra inventory is a fraction of the cost of rebuilding lost rank.

Ranking Requires Weekly Measurement, Not One-Time Optimization

A9 uses rolling behavioral data windows. A listing that was optimized three months ago and then left untouched will lose rank to a competitor actively managing their signals — even if your listing text is better. The sellers on page one are running weekly diagnostics on all seven factors covered here. That is the operational discipline that separates sustained ranking from temporary gains.

Operating Principle

Amazon ranks purchase probability, not listing quality. Optimise for what customers do — not just what they see. Measure behavioral signals weekly and act on data, not assumptions.

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Amazon Ranking Algorithm —Hidden Factors A9 Measures But Never Documents

All 7 Hidden Ranking Factors — At a Glance

The 7 Hidden Factors — Complete Breakdown

What to Do With This Information

Calculate Your PPC ProfitabilityAlongside Your Ranking Work

Amazon Ranking Algorithm —
Hidden Factors A9 Measures But Never Documents

Calculate Your PPC Profitability
Alongside Your Ranking Work