I’ve been trying to wrap my head around how Amazon calculates product star ratings, and I’ve got a few specific questions that I can’t find straight answers to:
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Text review vs. star-only rating — Is there a real difference in weight? Like, does a written review actually move the needle more than just clicking stars with zero text?
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Does rating correlate with sales volume? For example, do higher sales automatically make your rating better, or are they totally independent?
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International reviews — I have a UK listing with 100+ reviews at 4.9 stars. If I launch the same ASIN on the US marketplace, how much will those UK reviews affect my US rating? Are they treated the same as US-based reviews, or is there a penalty?
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Different types of reviews — Do star-only, text-only, text+photos, and video reviews all have different weight? Like, is a video review way more impactful than just a star?
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Real example that’s confusing me — Two products in the same category, both with 150 total reviews. Product A has 18 one-star reviews and ends up at 4.3 stars. Product B only has 8 one-star reviews (but 100 of its 150 reviews are star-only, no text) and also hits 4.3 stars. Does that mean star-only ratings have way lower weight… or are they basically useless?
I’d love to hear from anyone who’s dug into Amazon’s rating algorithm — what actually drives the score the most? Any insights would be a huge help!
Answers (3)
And honestly? Don’t overthink the exact numbers. Amazon tweaks their algorithm all the time, and the exact formula is secret. The best move is to consistently get high-quality verified reviews (text, photos, videos) and keep your product quality solid so you don’t get a ton of negatives. Everything else is just guesswork.
Quick add-on: Amazon’s rating algorithm isn’t a simple average — it’s weighted, and they don’t tell us the exact formula. But from what I can tell, it factors in:
Star-only ratings definitely have lower weight — that’s exactly why product B dropped to 4.3 with only 8 one-star reviews, while product A had 18. Product B’s positive reviews were mostly star-only, so they didn’t add much weight to offset the bad ones.
If you want a stable rating that can handle a few negative reviews, focus on verified purchase reviews with text (especially with photos/videos). Star-only ratings help a little when you’re just starting out, but they won’t protect you from a couple bad text reviews — those hit hard.
Based on my own testing and what I’ve picked up over the years, here’s the rough weight order I’ve noticed:
Also, the reviewer’s account quality matters a ton. A review from a top reviewer or a long-time Amazon shopper carries way more weight than a brand new account with zero history. And recency is big too — reviews from the last week hit way harder than ones from 6 months ago. I’ve seen ratings slowly drop over time if you don’t get new positive reviews coming in (total bummer, but it’s how it works).
As for international reviews: they do sync across marketplaces if you use the same ASIN, but they’re not quite as heavy as domestic reviews. Rough estimate — 2-3 international reviews are probably equal to 1 US review. Not nothing, but not the same.