The short answer: it depends almost entirely on how many reviews you already have. A business sitting at 4.7 with 100 reviews needs 20 more 5-star reviews to display 4.8. The same business with 500 reviews needs 100. With 1,000 reviews, it needs 200. The rating is a weighted average, so every review you have already collected is dead weight resisting the next one.
Most articles on this topic hand you a formula and leave. Below is the actual answer, computed for every realistic combination of rating and review count — the same maths that powers our free Google review score calculator.
How many 5-star reviews you need to reach the next milestone
Read this as: "I'm sitting at 4.6 with 250 reviews, so I need 36 more 5-star reviews to display 4.7." Every figure assumes your true average is exactly the rating shown, and that every new review is 5 stars.
| Sitting at | 25 reviews | 50 reviews | 100 reviews | 250 reviews | 500 reviews | 1,000 reviews |
|---|---|---|---|---|---|---|
| 4.0 | 2 | 3 | 6 | 14 | 27 | 53 |
| 4.2 | 2 | 4 | 7 | 17 | 34 | 67 |
| 4.4 | 3 | 5 | 10 | 23 | 46 | 91 |
| 4.5 | 2 | 6 | 12 | 28 | 56 | 112 |
| 4.6 | 4 | 8 | 15 | 36 | 72 | 143 |
| 4.7 | 3 | 10 | 20 | 50 | 100 | 200 |
| 4.8 | 9 | 17 | 34 | 84 | 167 | 334 |
| 4.9 | 15 | 50 | 100 | 250 | 500 | 1,000 |
Three things jump out of that table, and each one changes how you should plan.
1. The cost roughly doubles with every tenth you climb
At 100 reviews, going from 4.0 to 4.1 costs you 6 reviews. Going from 4.8 to 4.9 costs 34. Going from 4.9 to 5.0 costs 100. The climb gets steeper precisely as you get closer to the top, which is why so many businesses feel like their rating has "stalled" at 4.7 or 4.8 despite a steady stream of happy customers.
2. Review volume works against you
Every review already on your profile is an anchor. At 4.7, reaching 4.8 costs 20 reviews if you have 100 — but 200 if you have 1,000. Big review counts make your rating stable, which is excellent protection against a bad week and brutal when you are trying to climb.
The practical consequence: if you are early, fix your rating now. A course-correction at 40 reviews costs a handful of reviews. The same correction at 800 reviews costs a year of work.
3. Getting to a displayed 5.0 is close to impossible at scale
Look at the bottom-right of that table. A business at 4.9 with 1,000 reviews needs 1,000 more consecutive 5-star reviews to display 5.0 — it has to double its entire review history without a single blemish. This is why almost no established business shows a 5.0, and why chasing one is a poor use of your effort. 4.8 is an excellent, achievable target. 5.0 is a trap.
The rounding rule that costs businesses a whole star
Google displays one decimal place, and it rounds. That means you do not need to reach 4.8 to display 4.8 — you need to reach 4.75. It also means that at 4.7499 you are still showing 4.7, and a single review can tip you over.
| To display | Your true average must reach | At 4.74, Google shows |
|---|---|---|
| 4.5 | 4.45 | 4.4 |
| 4.6 | 4.55 | 4.5 |
| 4.7 | 4.65 | 4.6 |
| 4.8 | 4.75 | 4.7 |
| 4.9 | 4.85 | 4.8 |
| 5.0 | 4.95 | 4.9 |
This is the difference between "my rating won't move" and "my rating is about to move." Two businesses both displaying 4.7 can be in completely different positions: one at a true 4.652 has a long climb, while one at a true 4.749 is a single review away from 4.8. The displayed number hides this entirely.
This is exactly why the per-star breakdown matters. From your rating alone, you cannot know where in the band you sit. From your 1–5 star counts, you can know precisely.
The formula, if you want to check the maths
To find the number of additional 5-star reviews (x) needed to reach a target displayed rating T:
x ≥ (threshold × total − points) ÷ (5 − threshold)
where threshold = T − 0.05, total is your current review count, and points is the sum of all your star values (5 × your 5-star count, plus 4 × your 4-star count, and so on).
Worked example. You have 70 five-star and 30 four-star reviews. That is 100 reviews and 470 points, a true average of exactly 4.70. To display 4.8 you need a true average of 4.75, so:
x ≥ (4.75 × 100 − 470) ÷ (5 − 4.75) = 5 ÷ 0.25 = 20 reviews
Twenty consecutive 5-star reviews to move a single tenth. That is the real cost, and it is why a review strategy has to be a system rather than a campaign.
Stop estimating — get your exact number
The table above assumes your true average is exactly the rating Google displays. Yours almost certainly is not. To get the precise figure for your business, you need your actual 1–5 star breakdown, not just your average.
The free Google Review Score Calculator pulls your live star breakdown straight from Google, computes your exact average, and tells you precisely how many 5-star reviews stand between you and every remaining milestone. No signup, no email.
Related reading
- How Google calculates your star rating — the exact formula, and the rounding behaviour above.
- How to get more Google reviews — how to actually earn the reviews this page says you need.
- Why did my Google rating drop? — the same maths, running in reverse.