The details · Amazon
Amazon's star rating isn't a simple average, and newer reviews count more.
Verified-purchase reviews count for more too.
- From
- Case study · CS-002 · September 28, 2026
“Newer reviews carry more weight than older ones.”
What I found
Amazon uses "advanced models to calculate star ratings, not just a simple average." "Newer reviews carry more weight than older ones," and reviews from verified purchases are weighted higher.
So do this
Read your star rating as weighted, not averaged: Amazon counts newer reviews and verified-purchase reviews for more.
Keep in mind
Amazon says newer reviews count more than older ones. It doesn't say old ones disappear.
Source: What Amazon actually tells authorsCS3-125CS3-128
Read the full case studyI read eight Amazon algorithm guides. Here are two top factors, and the short list Amazon actually publishesWhat Amazon tells authors in its own words, what "we modeled it" really means, and the test model I'm building instead.Case study · CS-002 · 8 min read · 9 posts come from it