// FREE TOOL
Google review calculator: how many 5-star reviews do you need?
This Google review calculator works out how many more 5-star reviews it takes to lift your rating from where it sits today to the number you are aiming for. Enter your current rating and review count, set a target, and the answer updates as you type. The target is a true average, not a guaranteed displayed Google score. Calculate without signing up.
// THE CALCULATOR
Run your own numbers
Your current Google rating, how many reviews sit behind it, and the rating you want. Rough figures are fine, and the result recalculates on every keystroke.
You need about
// FREE ACTION PLAN
Get your free 90-day review plan
We will turn your target into a practical plan for asking consistently, protecting your rating and knowing what to do each week.
Your plan will use the rating target you entered above.
This estimates reviews needed for a true average, not a guaranteed displayed Google score. It assumes every new review is 5 stars. A rounded starting rating makes the result approximate; enter your full average if you know it.
The calculation runs in your browser. When analytics is enabled, we measure usage using rating, review-count and result ranges, plus your target. Requesting a review plan sends your figures and contact details to us; the contact link carries your result and target. See our privacy policy.
// THE MATHS
How the calculator works out the number
No black box. It is one line of arithmetic, and you can check it by hand in about ten seconds.
Reviews needed
(your review count × (target rating − current rating)) ÷ (5 − target rating)
Say you have 20 reviews averaging 4.4 stars and you want 4.8. That is 20 × 0.4 = 8, divided by 0.2, which gives 40. Forty consecutive 5-star reviews to move four tenths of a star.
The part that surprises people is the bottom of the fraction. It is the headroom between your target and a perfect 5.0, and it shrinks fast. At a 4.5 target you are dividing by 0.5, so every new review pulls half a star of weight. At a 4.9 target you are dividing by 0.1, so the same review does a fifth of the work. That one number is why the last two tenths of a star cost more than the first full star did.
Two honest caveats. The calculator assumes every review you get from here is a 5-star one, so treat the answer as a floor rather than a forecast. A displayed score loses precision, so using that as your starting average makes the result approximate. This tool targets the mathematical average; it does not guarantee when Google will update the number shown on your profile.
// HOW GOOGLE COUNTS IT
How Google actually works out your star rating
Worth knowing before you set a target, because three of these catch business owners out.
- 01 It is a plain average, with no recency bonus
Google describes your score as the average of all ratings published on your profile. There is no weighting for how recent a review is and no weighting for who left it. A 1-star review from three years ago pulls on your average with exactly the same force today as it did the week it landed.
- 02 A displayed score is less precise than the average
An average of 4.752 rounds mathematically to 4.8 at one decimal place. That explains why a rounded starting figure changes an estimate. Google's review-score help page does not specify an exact display threshold, so the calculator does not promise one.
- 03 The score can take up to two weeks to update
Google documentation says a published score can take up to two weeks to update after a new review arrives. If your rating has not moved the morning after a customer left one, that alone does not show a problem.
- 04 Removed reviews leave the average entirely
When Google takes a review down for breaching its policies, it stops counting. That is why a rating occasionally moves on a day nobody reviewed you.
- 05 Early reviews carry enormous weight
Starting with eight five-star reviews, one one-star review lowers the true average to about 4.556. Starting with 200 five-star reviews, it lowers the average to about 4.980. The same review has less effect when there are more ratings in the average.
// THE OTHER DIRECTION
Star rating calculator: your score from your star breakdown
The calculator above answers "how many more do I need". This star rating calculator runs the other direction: given the star breakdown Google already shows on your profile, what is your actual score to three decimal places?
Your true average
((1 × 1-stars) + (2 × 2-stars) + (3 × 3-stars) + (4 × 4-stars) + (5 × 5-stars)) ÷ total reviews
Take a profile with 2 one-star, 1 two-star, 3 three-star, 8 four-star and 26 five-star reviews. That is 2 + 2 + 9 + 32 + 130 = 175 stars across 40 reviews, so 175 ÷ 40 = 4.375. That rounds mathematically to 4.4 at one decimal place.
Worth doing once, because 4.375 and 4.4 are not the same starting point and the gap between them changes your answer. Type 4.375 into the calculator above rather than the 4.4 on your profile and the number it gives you is exact instead of approximate. The next section shows how much that matters.
// ACCURACY
Why two businesses both showing 4.4 need different numbers
This is the reason review calculators give you different answers for what looks like the same profile, and it is not that one of them is broken.
Under ordinary rounding to one decimal place, true averages from 4.35 up to (but not including) 4.45 round to 4.4. A rounded score can therefore hide different starting points. These examples use possible whole-star totals and compare the reviews needed for a true 4.5 average.
| 40 reviews, both round to 4.4 | True average | 5-star reviews to reach 4.5 |
|---|---|---|
| Business A | 4.35 (174 stars) | 12 |
| Business B | 4.425 (177 stars) | 6 |
Same rounded rating, same review count, and twice the work for one of them. Any calculator that only asks for your rounded rating, including this one on its default setting, has to assume you sit somewhere in that band. Work out your true average from the breakdown above, enter that instead, and the estimate stops being a range. That is the honest answer to whether these calculators are accurate: they are exactly as accurate as the starting number you hand them.
// REFERENCE
5-star reviews needed to reach 4.8 stars
The same formula, worked out for the review counts most small businesses are actually sitting on. Use the calculator above for your exact numbers.
| Current rating | If you have 20 reviews | If you have 50 reviews | If you have 100 reviews |
|---|---|---|---|
| 4.0 stars | 80 | 200 | 400 |
| 4.2 stars | 60 | 150 | 300 |
| 4.5 stars | 30 | 75 | 150 |
| 4.7 stars | 10 | 25 | 50 |
Read across any row and the pattern is the same: the more reviews you already have, the more it costs to move the average. Volume is what protects a good rating, and it is also what makes a bad one stubborn. Sitting on 100 reviews at 4.2 stars is a 300-review problem.
// ONE TENTH OF A STAR
How many 5-star reviews it takes to move your rating 0.1
Moving up 0.1 takes your review count × 0.1 ÷ (4.9 − your rating) new 5-star reviews. From 4.8 that is as many reviews as you already have.
| Moving from | If you have 20 reviews | If you have 50 reviews | If you have 100 reviews |
|---|---|---|---|
| 4.0 to 4.1 | 3 | 6 | 12 |
| 4.5 to 4.6 | 5 | 13 | 25 |
| 4.7 to 4.8 | 10 | 25 | 50 |
| 4.8 to 4.9 | 20 | 50 | 100 |
Worked through for 50 reviews at 4.5: 50 × 0.1 = 5, divided by 4.9 − 4.5 = 0.4, gives 12.5, so 13 reviews. The same tenth of a star from 4.8 divides by 0.1 instead, which is why it costs 50. Part reviews round up, because you cannot collect half a review.
// WORKED EXAMPLE
How many reviews to go from 4.8 to 4.9 stars with 26 reviews
Entering 26 reviews and a rounded 4.8 starting rating gives an estimate of 26 more 5-star reviews for a true 4.9 average. The exact answer depends on your actual star total, as the examples below show.
Using the rounded input: 26 × (4.9 − 4.8) ÷ (5 − 4.9) = 2.6 ÷ 0.1 = 26. Check it: the formula estimates 124.8 existing stars. Real reviews have whole-star ratings, so 124.8 cannot be the actual total of 26 reviews. This is why the answer from a rounded starting rating must stay an estimate.
With ordinary one-decimal rounding, star totals of 124, 125 or 126 across 26 reviews all round to 4.8. The table targets a true 4.9, not the threshold at which Google might display that number.
| 26 reviews, rounding to 4.8 | True average | 5-star reviews to reach a true 4.9 |
|---|---|---|
| 124 stars | 4.769… | 34 |
| 125 stars | 4.807… | 24 |
| 126 stars | 4.846… | 14 |
Check the middle row: 125 stars plus 24 × 5 gives 245 stars across 50 reviews, a true 4.9 average. Use your full starting average rather than the shortened decimals in this table. A review request system can help you ask customers consistently; it cannot control their ratings.
// THE PART NOBODY CALCULATES
How many 5-star reviews cancel out one 1-star review
Everyone asks how many 5-star reviews cancel out a bad one. The answer has a quirk in it that most people get wrong.
To get back to the exact average you had before a 1-star review landed, you need (your rating − 1) ÷ (5 − your rating) new 5-star reviews. Run that at any review count you like and the answer comes out the same. How many reviews you already have does not matter. Only the rating you are defending does.
| Rating you are protecting | 5-star reviews to undo one 1-star | What the number means |
|---|---|---|
| 4.0 stars | 3 | Returns to a true 4.0 average. |
| 4.3 stars | 5 | Whole reviews round up to reach or exceed the target. |
| 4.5 stars | 7 | Returns to a true 4.5 average. |
| 4.7 stars | 13 | Whole reviews round up to reach or exceed the target. |
| 4.8 stars | 19 | Returns to a true 4.8 average. |
| 4.9 stars | 39 | Returns to a true 4.9 average. |
The better your rating, the more expensive every bad review becomes. Climbing from 4.0 to 4.8 does not make you safer, it raises the cost of standing still from 3 reviews to 19. That is the argument for a steady weekly trickle of review requests rather than a burst every time someone notices the rating has slipped.
// PICKING A TARGET
Choose a target you can assess honestly
The default 4.8 is an example, not a recommended target for every business.
A true 5.000 average requires all ratings included in it to be five stars. Adding more five-star reviews cannot reach that exact average while a lower rating remains. A score displayed with fewer decimal places is a different question; the calculator does not predict Google's precise display threshold.
Compare 4.8 and 4.9 using your own starting numbers. Neither is universally achievable within a year: timing depends on customer volume, how many people choose to review and the ratings they give. Use the result to plan a consistent request process and address recurring feedback, rather than promise a score by a deadline.
// GETTING THERE
The reviews are out there, you just need a system to ask
A consistent request process makes it easier to invite feedback after completed work. Ask customers honestly, without incentives or selecting only those you expect to leave five stars. Their rating remains their choice.
A review system sends the request automatically the moment a job is marked complete, by text, with a one-tap link straight to your Google profile. Every customer gets the same link and it always goes to the public review page. Screening people by how happy they seem before you show them the link breaches Google policy, so we do not build it that way. The volume comes from asking everyone promptly, not from choosing who gets asked.
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// COMMON QUESTIONS
Questions about the review maths
Anything the calculator did not answer? Ask us directly and we'll give you a straight answer, no jargon, no pressure.
Get in touchHow is a Google review score calculated?
Google describes the score as the average of all published ratings. Multiply each star level by its review count, add those totals and divide by all reviews. For example, 175 stars across 40 reviews gives a true average of 4.375. The score displayed on a profile is less precise. This tool calculates a true-average target, not a guaranteed Google display threshold. Google says a new review can take up to two weeks to affect the published score.
Are Google review calculators accurate?
The formula assumes the current average is accurate and every new review is five stars. A rounded rating loses information: 40 reviews totalling 174 stars have a true 4.35 average and need 12 more five-star reviews to reach 4.5; 177 stars give 4.425 and need 6. Both round mathematically to 4.4. Enter your full average when available. The tool does not predict which reviews Google will publish or when its displayed score will change.
I got 100 new 5-star reviews and my rating has not moved. Why?
A large review base can make the change small. A business with a true 4.6 average across 900 reviews reaches 4.64 after 100 additional five-star reviews; both values round mathematically to 4.6. That is an illustration, not a guarantee of Google display behavior. Also check which reviews were published or removed. Google says score updates can take up to two weeks.
How many 5-star reviews do I need to cancel out a 1-star review?
Divide your current rating minus 1 by 5 minus your current rating. At 4.5 stars that is 3.5 divided by 0.5, so 7 five-star reviews. At 4.8 stars it is 19. The answer does not depend on how many reviews you already have, only on the rating you are protecting, which is why a high rating gets more expensive to defend rather than easier.
What happens when you hit 100 reviews on Google?
There is no special threshold in this calculation. With 20 reviews averaging 4.8, one new one-star review lowers the true average to about 4.619. With 100 reviews averaging 4.8, it lowers the true average to about 4.762. A larger base reduces the effect of any single review; this does not establish a special Google ranking or display rule at 100 reviews.
How many reviews do I need to go from 4.5 to 4.8 stars?
Roughly one and a half times the number of reviews you already have. At 20 reviews that is 30 more 5-star reviews, at 50 reviews it is 75, and at 100 reviews it is 150. The calculator on this page gives you the exact figure for your own numbers.
Can I actually reach a 5.0 rating on Google?
An exact 5.000 average requires every rating still included in the average to be five stars. That is different from a displayed score with fewer decimal places. One four-star plus 99 five-star reviews averages 4.99, which rounds mathematically to 5.0 at one decimal place. Google does not specify an exact display-rounding threshold in its review-score help page, so this calculator does not promise what your profile will show.
How long does a new review take to change my rating?
Google states that it can take up to two weeks for a new review to be reflected in your published score. If the number on your profile has not moved the day after a customer left a review, that is normal and not a sign the review was rejected.
Can I get a bad review removed instead?
Only if it breaches Google review policies, for example if it is spam, off topic, or from someone who was never a customer. You can flag it and Google will assess it, but most genuine negative reviews stay up. Outweighing it with real reviews is the path you actually control, and the table on this page tells you what that costs.
Is this Google review calculator free to use?
Yes. Calculation runs in your browser without signup. When analytics is enabled, usage events include rating, count and result ranges plus your target rating. If you request a review plan, your entered figures and contact details are sent to us; the contact link also carries the result and target. See our privacy policy for measurement and enquiry handling. An embed snippet is available at the bottom of this page.