Amazon Review Rating Calculator
See how many new 5-star ratings it takes to move your average, and how many 1-star ratings you could absorb before it drops.
Your numbers
The global ratings count under the stars, not just written reviews.
Your result · updates as you type
5-star ratings needed
108
180 ratings at 4.2 plus 108 new ratings at 5 brings the average to 4.5 stars.
- Ratings after
- 288
- Share that must be new
- 38%
- Stars in total now
- 756
Amazon's displayed rating may not be a plain average of every rating, so treat this as a close estimate. Use Request a Review in Seller Central or the Amazon Vine program to earn ratings; paying for or filtering reviews breaks Amazon's policies.
Breakdown
- Formula
- count × (target − current) ÷ (new stars − target)
- Worked through
- 180 × (4.5 − 4.2) ÷ (5 − 4.5) = 108
- Rounded up
- 108
The formula
Worked example (the calculator's starting values)
- Current rating
- 4.2 stars, 180 ratings
- Target
- 4.5 stars
- New ratings expected
- all 5-star
180 × (4.5 − 4.2) ÷ (5 − 4.5) = 108 new 5-star ratings needed, rounded up. That brings 288 total ratings to a 4.5 average.
On a smaller listing (3.9 stars, 60 ratings, target 4.3), it only takes 35 new 5-star ratings, since the smaller base moves faster.
What it doesn't show
- Amazon's displayed rating isn't always a plain average. Amazon says it uses a machine-learned model that can weight recent ratings and other factors, so treat this as a close estimate rather than an exact count.
- How many 1-star ratings you can absorb. When you're already at or above target, the calculator shows how many 1-star ratings would pull you back below it, so you know how much cushion you have.
- Getting the ratings is a separate problem. Use Amazon's Request a Review button in Seller Central, or the Vine program for new listings. Paying for reviews, offering free products for reviews, or filtering who gets asked all break Amazon's review policies.
Questions people ask
How many 5-star reviews do I need to raise my rating?
It depends on your current rating and rating count. The formula is current count × (target − current) ÷ (5 − target). A listing at 4.2 stars with 180 ratings needs 108 new 5-star ratings to reach 4.5.
Why does a bigger listing need more new reviews to move its rating?
The current rating is a weighted average over every existing rating, so a listing with thousands of ratings needs proportionally more new ones to shift the average by the same amount as a smaller listing.
Is Amazon's star rating a simple average?
Amazon says its rating uses a machine-learned model rather than a plain average, so treat any calculation like this as a close estimate, not an exact figure.
How do I legitimately get more Amazon reviews?
Use the Request a Review button in Seller Central for eligible orders, or enroll new products in the Amazon Vine program. Buying reviews or asking only satisfied customers for reviews violates Amazon's policies.
How many bad reviews can I take before my rating drops?
The calculator's "1-star ratings you can absorb" figure shows this when you're already at or above your target rating, based on your current count and rating.
Related tools
Want this builtinto your store?
I'm Emmanuel, a Shopify and WooCommerce developer. If this tool pointed at something you'd rather have fixed for you (a faster store, cleaner product data, a migration, a custom feature), send me a note.
Emmanuel Asika
Shopify & WooCommerce developer, Dublin
I build and fix online stores: new builds, migrations, speed, SEO and the custom bits apps can't do.
Last reviewed 30 September 2026.