Google Review Calculator: How Many 5-Star Reviews Do You Need?
Enter your rating, your target and your review count: this Google review calculator returns the number of 5-star reviews to collect. Free, no sign-up.
In short. The number of 5-star reviews you need equals your current review count multiplied by the gap to close, divided by 5 minus the target rating. A business at 4.2 with 30 reviews needs 18 five-star reviews to display 4.5. The higher the target, the more each tenth costs: going from 4.8 to 4.9 takes almost as many reviews as you already have. In our observatory of 1,800 Google listings, the rating does not separate the best-ranked businesses from the rest (4.62 in both groups); review volume does: a median of 738 reviews in the top 5 versus 300 for positions 16 to 20.
Google Review Calculator
Determine precisely the effort needed to reach your e-reputation goals.
How the calculation works
Google displays the average of all ratings, rounded to one decimal. To raise it, low ratings must be diluted in new 5-star ratings. The formula: reviews needed = current reviews × (target − current rating) ÷ (5 − target), rounded up.
Three examples with this formula:
| Situation | Target | 5-star reviews needed |
|---|---|---|
| 3.8 with 20 reviews | 4.2 | 10 |
| 4.2 with 30 reviews | 4.5 | 18 |
| 4.6 with 120 reviews | 4.8 | 120 |
The last row says it all: above 4.5, each tenth costs more and more reviews, because no new review can exceed 5. That is why 5.0 is out of reach as soon as a single review is below 5.
What a single negative review costs
Before chasing a rating, measure what you risk. A 1-star review removes 0.336 points from a listing with 10 reviews rated 4.7, but only 0.005 points from a listing with 700 reviews. Volume is your best protection.
And to cancel that review afterwards, you need more 5-star reviews the higher your starting rating: 3 reviews at 4.0, 19 at 4.8, 39 at 4.9.
Real thresholds by sector
The calculator gives a rating target. But to be visible on Google Maps, the number of reviews matters more. On 25 September 2026 we recorded the top 20 results for 9 sectors in 10 large French cities. The entry threshold is the first quartile: 75% of visible businesses have more reviews than this figure.
| Sector | Entry threshold | Top 20 median | Median rating |
|---|---|---|---|
| Cinema | 44 | 414 | 4.40 |
| Street food | 108 | 310 | 4.80 |
| Bakery | 123 | 266 | 4.65 |
| Bowling | 130 | 693 | 4.40 |
| Hair salon | 155 | 249 | 4.80 |
| Optician | 155 | 250 | 4.90 |
| Gym | 180 | 386 | 4.60 |
| Escape game | 202 | 826 | 4.90 |
| Restaurant | 388 | 708 | 4.80 |
These thresholds are for large cities; in a mid-size town they are much lower. The breakdown by city and the method are in our article on review thresholds by sector.
How to get those reviews
Once you know the number, the hard part is keeping the pace. Three levers, in the order of effectiveness we measure with our clients: a review QR code at the till or on the table, an SMS or email request after the visit, and a reply to every review to show you read them. Never offer anything in exchange for a review: Google forbids it and removes incentivised reviews.
Watch
Collect reviews
Chapters
- Get more Google reviews: 12 techniques
- Review QR codes: create them and measure results
- Does replying to reviews boost your listing?
GMB Club automates collection by QR code, SMS and email, syncs your reviews and the Reviews Agent drafts a reply for you to approve.
Frequently asked questions
- How many reviews to go from 4.5 to 4.8?
- With 50 reviews you need 75 five-star reviews; with 100 reviews, 150. Formula: reviews × (4.8 − 4.5) ÷ (5 − 4.8).
- Can you reach 5.0?
- Only if every review is 5 stars. As soon as one review is lower, the average stays below 5, although Google may display 5.0 by rounding when 5-star reviews are very numerous.
- Is a good rating enough to rank well on Google Maps?
- No. In our observatory, the top 5 and positions 16 to 20 share the same average rating, 4.62. What separates them is review volume: a median of 738 versus 300.
- How long does it take to raise a rating?
- It depends on your collection pace. In the sectors we track, top 10 listings receive 3 to 25 reviews a month depending on the trade. Divide the reviews you need by your real monthly pace.
GMB Club calculations. Data from the Google listings observatory, recorded on 25 September 2026: 1,800 listings, 9 sectors, 10 cities. Page updated 2 October 2026.
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