Reviews
How Many 5-Star Reviews Do You Need to Reach 4.5 (or 4.8) on Google? Simple Calculator and Tables
Want to lift your Google rating from 3.8 to 4.5, or 4.4 to 4.8? Learn the simple formula to calculate how many new 5-star reviews you need, ready-made tables for common starting points, why Google's displayed rating rounds, why one bad review hurts small profiles more, realistic timelines, and a policy-safe plan to get there.
By Chamko Research Team Updated 5 min read
Quick answer
Use this formula: new 5-star reviews needed = N × (target − current) ÷ (5 − target), where N is your current number of reviews. For example, with 100 reviews at 4.2 and a target of 4.5: 100 × 0.3 ÷ 0.5 = 60 new 5-star reviews. Reaching 4.8 from 4.2 would need 100 × 0.6 ÷ 0.2 = 300. Higher targets get much harder, so most businesses aim for 4.5–4.7 with a steady flow of genuine reviews and fixes for the problems behind low ratings.
Quick answer: Use this formula: new 5-star reviews needed = N × (target − current) ÷ (5 − target), where N is your current number of reviews. For example, with 100 reviews at 4.2 and a target of 4.5: 100 × 0.3 ÷ 0.5 = 60 new 5-star reviews. Reaching 4.8 from 4.2 would need 100 × 0.6 ÷ 0.2 = 300. Higher targets get much harder, so most businesses aim for 4.5–4.7 with a steady flow of genuine reviews and fixes for the problems behind low ratings.
Understanding the maths helps you set realistic goals and stay motivated (improve rating from 3.5 to 4.5).
The formula
Your average rating is the total of all stars divided by the number of reviews. If you add only 5-star reviews:
x = N × (T − R) ÷ (5 − T)
- N = current number of reviews
- R = current rating
- T = target rating
- x = new 5-star reviews needed
Google's displayed rating is rounded (usually to one decimal place), so aim slightly above your target.
Ready-made table: 50 reviews
| Current | Target 4.3 | Target 4.5 | Target 4.7 |
|---|---|---|---|
| 3.8 | 36 | 70 | 150 |
| 4.0 | 22 | 50 | 117 |
| 4.2 | 8 | 30 | 84 |
Figures are rounded up to whole reviews and assume every new review is 5 stars.
Worked examples
Small profile: 20 reviews at 4.0, target 4.5
x = 20 × 0.5 ÷ 0.5 = 20 new 5-star reviews.
Medium profile: 150 reviews at 4.1, target 4.5
x = 150 × 0.4 ÷ 0.5 = 120.
Large profile: 600 reviews at 4.3, target 4.6
x = 600 × 0.3 ÷ 0.4 = 450.
Hard target: 100 reviews at 4.5, target 4.9
x = 100 × 0.4 ÷ 0.1 = 400.
Each step closer to 5.0 gets much harder.
Why one bad review hurts small profiles more
With 10 reviews averaging 5.0, one 1-star review drops you to about 4.6. With 200 reviews at 5.0, one 1-star review drops you only to about 4.98. Building review volume protects your rating (first review negative).
Not every new review will be 5 stars
Realistically, some new reviews will be 4 stars. If your new reviews average 4.8 instead of 5.0, replace "5" in the formula with 4.8:
x = N × (T − R) ÷ (4.8 − T)
This shows why fixing service problems matters: if new reviews average below your target, your rating won't rise no matter how many you collect.
Realistic timelines
If you get 5 new reviews a week, 60 reviews takes about 12 weeks. Steady weekly reviews are better than sudden bursts, which can be filtered (review velocity, fake review warning).
Is 5.0 the goal?
Not usually. Many customers trust 4.6–4.8 more than a perfect 5.0, which can look suspicious (rating psychology).
A policy-safe plan to raise your rating
- Fix root causes behind low ratings: waiting time, rude staff, quality (review topics).
- Ask every happy customer at the moment of satisfaction (how to ask, request templates).
- Reply to every review (how to reply).
- Report fake reviews that break policy (remove a Google review).
- Track weekly progress in a sheet.
Never buy reviews, offer incentives or ask only happy customers through a filter (review incentives).
Track it in a sheet
Columns: week, total reviews, rating, new reviews, average of new reviews. Plug numbers into the formula monthly to see how far you are from your target.
Example: a restaurant at 3.9
A restaurant with 220 reviews at 3.9 wanted 4.3. The formula said 220 × 0.4 ÷ 0.7 ≈ 126 five-star reviews. It fixed slow weekend service, added table QR codes and averaged 15 new reviews a week, mostly 5 stars. It reached 4.3 in about nine months.
Example: a new salon
A salon with 12 reviews at 4.2 needed just 12 × 0.4 ÷ 0.4 = 12 more 5-star reviews to reach 4.6. It got there in a month by asking every satisfied client.
Checklist
- Note current reviews and rating
- Choose a realistic target (4.5–4.7)
- Calculate reviews needed
- Fix the causes of low ratings
- Ask every happy customer
- Track weekly
Key takeaways
- Use x = N × (T − R) ÷ (5 − T) to set goals.
- Targets near 5.0 get exponentially harder.
- Fixing service problems matters as much as collecting reviews.
Sources and further reading
- Google Business Profile Help — reviews: support.google.com/business
- Google rating dropped suddenly
Ready-made table: 200 reviews
| Current | Target 4.3 | Target 4.5 | Target 4.7 |
|---|---|---|---|
| 3.8 | 143 | 280 | 600 |
| 4.0 | 86 | 200 | 467 |
| 4.2 | 29 | 120 | 334 |
The same improvement needs four times as many reviews when you start with four times as many. Larger profiles move slowly, but they're also more stable when a bad review arrives.
Frequently asked questions
How many 5-star reviews to go from 4.0 to 4.5?
As many as your current number of reviews (N × 0.5 ÷ 0.5 = N).
Why is 4.9 so hard to reach?
Because the remaining gap to 5.0 is tiny, so each review moves it less.
Does Google round the rating?
Yes, the displayed rating is rounded.
Will 4-star reviews help?
Only if your target is below 4.0.
How fast can I raise my rating?
Depends on review volume; steady weekly reviews are best.
Is a 5.0 rating good?
It can look less believable than 4.7–4.8.
Does the formula work for any number of reviews?
Yes — just plug in your current count and rating.
What if some new reviews are 4 stars?
Use the average of your new reviews instead of 5 in the formula.