How Amazon's A9 Algorithm Works
Before you write a single word, understand this: Amazon's algorithm ranks products based on relevance and sales velocity. Relevance comes from your copy (title, bullets, description, backend keywords). Sales velocity comes from conversion rate.
This means your listing needs to do two things simultaneously — include the right keywords to get found, and be persuasive enough to convert people once they land on your page. Let's break down each section.
1. The Product Title
200 characters maxThe title is your single most important keyword placement. Amazon's algorithm weighs title keywords heavily. But the title also needs to be readable — a wall of keywords with no structure hurts conversion.
The recommended title format:
❌ Bad title
Great Wireless Earbuds Best Quality Premium Sound Comfortable Fit Music Headphones for All
✓ Good title
SoundCore Wireless Earbuds, Active Noise Cancelling, 30H Battery, IPX5 Waterproof, USB-C, Black
→ Put your most important keyword in the first 80 characters (what mobile displays)
→ Never use promotional language: 'Best', 'Sale', '#1', 'Amazing'
→ Don't use ALL CAPS in the title (reserved for bullets)
→ Separate elements with commas — not pipes (|)
2. The Bullet Points
255 chars each × 5Bullet points are where you convert. Most buyers make their decision here — not in the description. Each bullet needs to answer: “what does this feature do for me?”
The bullet formula:
❌ Feature only
• 30 hour battery life
✓ Feature + benefit
• EXTENDED 30-HOUR BATTERY – Power through a full workweek on a single charge. Swap USB-C top-up runs from 0 to full in 60 minutes.
❌ Feature only
• IPX5 waterproof rating
✓ Feature + benefit
• SWEAT & RAIN PROOF (IPX5) – Run in the rain, push through intense workouts, and never worry about moisture damage again.
Structure your 5 bullets strategically:
→Bullet 1: Your headline feature — the thing you'd put on the box
→Bullet 2: Second strongest differentiator
→Bullet 3: A benefit that removes a common buyer concern
→Bullet 4: Technical spec that signals quality (materials, certifications)
→Bullet 5: Compatibility, package contents, or guarantee
3. The Product Description
2000 characters maxMost sellers ignore the description. That's a mistake for two reasons: it's indexed by Amazon's algorithm, and it's where undecided buyers go when bullets weren't enough.
Description structure:
Start with the buyer's situation, not your product. 'For anyone who's ever had earbuds die mid-flight...' is more compelling than 'Introducing the SoundCore Pro.'
Why does this product exist? What problem was it designed to solve? This is the 'why' that separates premium products from commodities.
Expand on your top 2–3 bullets with more detail. Address common hesitations (durability, compatibility, ease of use).
'Add to Cart' style language. 'Order today and start your mornings with sound that doesn't disappoint.'
4. Backend Search Terms
Backend keywords are invisible to buyers but indexed by Amazon. This is where you put keyword variations, synonyms, common misspellings, and complementary use cases that didn't fit naturally in your title or bullets.
Rules for backend keywords:
- → 250 characters maximum (Amazon counts bytes, not characters — stay under 200 to be safe)
- → Separate with spaces, not commas — commas waste character space
- → Don't repeat keywords already in your title (Amazon already indexes those)
- → Include synonyms: 'headphones' + 'earphones' + 'earbuds' + 'in-ear headphones'
- → Include common misspellings if they have search volume
- → Include complementary use cases: 'for running' + 'for gym' + 'for travel'