Free tool
Google review rating calculator
Enter your current average rating, how many reviews you have and the rating you want. The page gives the number of new 5-star reviews that gets there, with the arithmetic shown. Nothing you type leaves your browser.
By Hamza Rivera, updated
Short answer: The number of new 5-star reviews needed to reach a target Google rating is the review count times (target minus current average), divided by (5 minus target), rounded up to a whole review. With 50 reviews at 4.2 and a target of 4.5, that is 30 reviews. The arithmetic is exact for the numbers you enter, while the rating Google displays may be rounded. This browser calculator does the sum for your own figures.
Reviews are one part of a profile. The rest is covered in our Google Business Profile optimization service.
What it takes
- New 5-star reviews needed
- 30
- Review count after
- 80
- Average after
- 4.500
Other targets from the same starting point
The same current average and review count, against a few higher targets. Targets at or below your current average are left out.
| Target rating | New 5-star reviews |
|---|---|
| 4.3 | 8 |
| 4.5 | 30 |
| 4.7 | 84 |
| 4.8 | 150 |
| 4.9 | 350 |
The formula
An average is the total of all the stars divided by the number of reviews. With N reviews at an average of C, the stars add up to N times C. Add n reviews of five stars each and the new average is (N times C plus 5 times n) divided by (N plus n). Set that equal to the target T and solve for n:
n = N times (T minus C), divided by (5 minus T), rounded up
The rounding goes up because you cannot collect part of a review, and one review short leaves the average just under the target. Take 50 reviews at 4.2 with a target of 4.5: 50 times 0.3 is 15, divided by 0.5 is 30. Thirty 5-star reviews bring the stars to 210 plus 150, which is 360 across 80 reviews, an average of exactly 4.5.
The result is exact for the numbers you enter. Google shows a rounded average, so the figure you type in can sit a little away from the exact one, and the rating on the profile may be rounded as well. Use the result as a close estimate and check the displayed rating as the reviews arrive. It also assumes every new review is 5 stars and that no lower review comes in meanwhile. Each one that does raises the total.
The pattern in the table is worth a look. The closer the target is to 5, the faster the number climbs, because each 5-star review moves the average by a smaller amount the nearer it already is to 5. A profile with many reviews also moves slowly. A higher target is quick to reach with a small review count and slow with a large one.
Getting the reviews
Ask real customers, after real work, all of them. Do not buy reviews, do not offer a discount or a prize for one, and do not send the request only to customers you expect to be happy. Google treats those as policy violations, and a figure from this page is no reason to bend them. Our post on getting Google reviews without breaking the policy sets out what is allowed, and the review link and QR code generator gives customers a one-tap route to the form.
To see how a profile is doing beyond its rating, read the Business Profile performance report explained, and for how Google orders local results, see how Google ranks local results. Passieon is an independent agency and is not affiliated with Google.
Questions about review ratings
What is the formula for the number of 5-star reviews needed?
Reviews needed = review count times (target minus current average), divided by (5 minus target), rounded up to the next whole review. With 50 reviews at 4.2 and a target of 4.5, that is 50 times 0.3, divided by 0.5, which is 30.
Why can the target never be 5.0?
The formula divides by 5 minus the target. At a target of 5 that is zero, and with any review below 5 stars already on the profile, no number of new 5-star reviews brings the average to exactly 5. The page asks for a target below 5.
Does Google round the rating it shows?
Google shows the rating to one decimal place, so you cannot see the exact average. The arithmetic on this page is exact for the numbers you type in, so treat the result as a close estimate.
Does this assume every new review is 5 stars?
Yes. The calculation counts only 5-star reviews and assumes no other review arrives while you collect them. Any 4-star or lower review that lands in between raises the number you need.
How should I get the reviews?
Ask real customers, all of them, after a real job. Do not pay for reviews, offer a reward for them, or ask only the customers you expect to be happy. Google’s policy treats those practices as violations, and our post on getting reviews within the policy covers what is allowed.
Is anything I type here sent anywhere?
No. Everything happens in your browser. There is no form submission, no analytics event and no network request of any kind, which you can confirm in your browser’s network tab.
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