Your star rating is one of the biggest factors in conversion rate on Amazon. This tool shows you exactly how many new 5-star reviews you need to move your average rating up — and how many 1-star reviews it takes to drag it down.
The Formula
To find how many new 5-star reviews (n) you need to reach a target rating (T), given your current rating (R) and current review count (C):
| Step | Formula |
|---|---|
| Current total stars | R × C |
| Reviews needed (n) | C × (T − R) ÷ (5 − T) |
| New rating after n reviews | (R × C + 5n) ÷ (C + n) |
Worked Example
You’re at 4.2 stars with 150 reviews and want to reach 4.5 stars:
| Input | Value |
|---|---|
| Current Rating | 4.2 |
| Current Reviews | 150 |
| Target Rating | 4.5 |
| New 5-Star Reviews Needed | 90 |
Quick Reference: Reviews Needed to Reach 4.5★ (from 100 existing reviews)
| Current Rating | Current Reviews | 5-Star Reviews Needed for 4.5★ |
|---|---|---|
| 3.8 | 100 | 140 |
| 4.0 | 100 | 100 |
| 4.2 | 100 | 60 |
| 4.4 | 100 | 20 |
| 4.6 | 100 | 0 (already above target) |
Notes on the Math
- Amazon actually weights recent reviews more heavily than a simple average, so real movement is often faster than the raw math suggests.
- The same formula works in reverse to see how many 1-star reviews it would take to drop your rating — just substitute 1 for 5 in the numerator.
- Only use Amazon-compliant review generation: the “Request a Review” button, Amazon Vine, and good post-purchase follow-up. Never offer incentives for reviews.
Need your exact numbers calculated? Tell us your current rating and review count and we’ll map out your path to your target rating.
