How Many 5-Star Reviews Do You Need to Improve Your Rating?
The math behind moving a star rating, explained in plain language — plus a calculator that does it for you.
For a platform with a simple average rating, the number of 5-star reviews needed to hit a target is pure math — the challenge is that the number grows faster than most people expect as your review count increases.
The formula
For a simple average, the reviews needed (n) to move from a current rating to a target rating, given your existing review count, follows this relationship: n = existing reviews × (target − current) ÷ (5 − target). It solves for how many perfect reviews it takes to pull the average up to where you want it.
A worked example
A business with 40 reviews averaging 3.8 stars wants to reach 4.5. Using the formula: 40 × (4.5 − 3.8) ÷ (5 − 4.5) = 40 × 0.7 ÷ 0.5 = 56 five-star reviews. That’s more than the business’s entire existing review count — a useful gut-check for why rating recovery takes sustained effort, not a quick push.
Why it gets harder as you grow
The more reviews you already have, the more new 5-star reviews it takes to move the average by the same amount — the math scales with your existing base. This is also why one bad week doesn’t sink an established business’s rating the way it would a brand-new one, and why a mature profile takes longer to meaningfully shift in either direction.
A caveat for weighted platforms
This formula assumes a simple average — accurate for Google Reviews. Platforms like Trustpilot use a weighted calculation (see our TrustScore guide), so treat any projection there as a rough estimate, not an exact number.
Frequently asked questions
Yes — see our Rating Recovery calculator, which runs this formula for you based on your current rating, review count, and target.