Calculate reviews needed
Choose a target average, then compare the result with the assumptions below it. The starting scenario assumes every new review is five stars. You can change that assumption in the additional options.
Free to calculate. No login, email address or Google-account connection required.
The interactive calculator needs JavaScript. You can still use the formula and worked examples below to calculate an estimate.
Illustrative example
About your result: using a displayed rating gives an estimate. Known star counts remove that input uncertainty only when they cover all the current published ratings. Future ratings and changes to existing reviews can still change the outcome.
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How to use the Google review calculator
Start with the rating and review count shown for the correct business in Google Search or Maps. Use figures from the same profile and the same check, rather than combining an old rating with a newer count. Google displays review scores and total review counts for businesses in these services. See Google's explanation of review scores.
Enter those two figures and choose your target average. For a first comparison, leave new reviews set to five stars. Then try a lower assumed average to see how the estimate changes when future feedback is mixed.
The result is a number of additional published ratings, not a number of customers to contact. Sending 30 requests does not establish that 30 people will publish a review or choose the same rating.
When you have a complete count of each star level, switch to Use my star counts and enter the number of one-, two-, three-, four- and five-star ratings, including zero where applicable. The calculator derives the total and average from those counts. Do not estimate the counts from the widths of a rating chart or use only the latest reviews as though they were the whole profile.
If the calculator reports that the rating and count do not fit its rounding model, recheck the figures for the same profile. The inputs may be out of date, or the model may not match the displayed score.
How the Google review calculator works
Google says a business's review score is the average of all ratings published on Google for that business. The calculator applies that averaging principle to your inputs and chosen future-rating scenario. Read the official averaging definition.
Average rating = total stars ÷ number of ratings
For example, ten four-star ratings and ten five-star ratings contribute 90 stars across 20 ratings. Their average is 90 ÷ 20 = 4.5.
To calculate how many additional five-star reviews would reach or exceed a higher target below five:
Additional five-star reviews = (target average × current review count − current total stars) ÷ (5 − target average), rounded up to a whole review.
An exact-average target means an unrounded threshold, not a promise to land on that number exactly. Whole reviews can take you past it. For example, one four-star rating followed by one five-star rating averages 4.5, so that single new review reaches or exceeds a target of 4.2.
If you use the displayed rating instead of known star counts, the basic calculation estimates total stars by multiplying that rating by the review count. The rounded-rating range shows how the answer can vary under the stated rounding model.
Example: moving from 4.2 to an exact 4.5 average
A business with 50 ratings averaging exactly 4.2 has 210 stars in total. Reaching an exact 4.5 average requires 30 additional five-star ratings:
(4.5 × 50 − 210) ÷ (5 − 4.5) = 30
Those new ratings add 150 stars. The new total is 360 stars across 80 ratings, and 360 ÷ 80 = 4.5.
| Stage | Number of ratings | Total stars | Average |
|---|---|---|---|
| Starting point | 50 | 210 | 4.20 |
| After 29 additional five-star ratings | 79 | 355 | About 4.494 |
| After 30 additional five-star ratings | 80 | 360 | 4.50 |
Illustrative calculation, not a client result. The starting average is known exactly, all additional ratings are five stars, and no existing ratings change.
The 29-review result is close to 4.5, but it is still below an exact 4.5 average. A rounded display and an exact-average target are different things.
How many 5-star reviews cancel a 1-star review?
There is no single number that works for every rating. To return to at least your previous exact average after one additional one-star review, you would need 7 five-star reviews at a previous average of 4.5, 19 at 4.8, or 39 at 4.9.
“Cancel” means offsetting the effect on the average. It does not erase the one-star review.
| Exact average before the new one-star review | Additional five-star reviews needed to return to at least that average |
|---|---|
| 4.0 | 3 |
| 4.2 | 4 |
| 4.5 | 7 |
| 4.7 | 13 |
| 4.8 | 19 |
| 4.9 | 39 |
| 5.0 | No finite number while the one-star review remains |
Illustrative recovery scenarios: one new one-star rating, followed only by five-star ratings, with all existing ratings unchanged. Starting averages are exact, not merely displayed scores.
For a previous exact average below five, the recovery formula is:
Five-star reviews needed = (previous average − 1) ÷ (5 − previous average), rounded up.
At an exact 4.8 average, a new one-star rating falls 3.8 stars below that average. Each new five-star rating contributes only 0.2 stars above it. That is why restoring the old average takes 3.8 ÷ 0.2 = 19 five-star ratings.
Your starting review count cancels out of this particular calculation because the goal is to return to at least that same exact average. It still matters when calculating the size of the initial drop or reaching a different target.
What does one more review do to your current average?
With 50 ratings averaging exactly 4.2, one new five-star rating would make the average about 4.216. One new one-star rating would make it about 4.137.
A larger review history makes either change smaller. For a different task—raising an exact 4.2 average to an exact 4.5—50 existing ratings need 30 additional fives, 100 need 60, and 200 need 120.
To plan after a low rating has already appeared, use the current rating and review count in the main calculator. To understand restoration of a previous average, use the table above with its stated conditions. Do not add the same one-star review twice.
Why can Google review calculators give different answers?
Calculators can use different starting assumptions and different targets. One may treat your displayed 4.2 as exactly 4.20; another may allow for a range. One may calculate an exact 4.5 average; another may calculate a lower average that would round to 4.5 under its chosen model.
An exact average and a displayed rating are not the same target
Starting from 50 ratings with an exact average of 4.20:
| Calculation | Additional five-star ratings |
|---|---|
| Reach an exact average of 4.50 | 30 |
| Reach 4.45, which would round to 4.5 under a conventional nearest-tenth model | 23 |
The second row is a rounding simulation, not a guarantee about Google's next displayed score. Google's review-score help page explains averaging but does not specify the threshold or tie-breaking method used in this simulation.
Our simulation rounds to the nearest tenth, with halfway values rounded up. It must be read with that assumption. The main calculator's default target remains the mathematical average you entered.
Known star counts can change the answer
Under that same conventional rounding model, these three rating histories each have 50 ratings displaying 4.2, but their underlying averages differ:
| Illustrative star-count breakdown | Total stars | Exact average | Additional fives to reach an exact 4.5 |
|---|---|---|---|
| 42 four-star ratings and 8 five-star ratings | 208 | 4.16 | 34 |
| 40 four-star ratings and 10 five-star ratings | 210 | 4.20 | 30 |
| 38 four-star ratings and 12 five-star ratings | 212 | 4.24 | 26 |
These are examples, not observed business profiles. For 50 whole-star ratings displaying 4.2 under this model, the feasible total runs from 208 to 212 stars. That gives a range of 26–34 additional five-star ratings to reach an exact 4.5.
This is why a result such as “30 reviews” should not be presented as an exact answer when the only starting information is a rounded display. Enter complete star counts when available; otherwise, use the estimate and its range as planning information.
What changes if some new reviews are below 5 stars?
A lower average among new reviews means you need more of them to reach the same higher target. The all-five-star scenario is a best-case calculation, not a prediction of customer feedback.
For the same 50 ratings averaging exactly 4.2, targeting an exact 4.5:
| Assumed average of new ratings | Additional ratings required by the model |
|---|---|
| 5.0 | 30 |
| 4.8 | 50 |
| 4.6 | 150 |
| 4.5 or lower | The target cannot be reached from below under this assumption |
Illustrative projections with existing ratings unchanged. An assumed future average does not guarantee the mix or timing of actual reviews.
For example, 40 new five-star ratings and 10 new four-star ratings have a combined average of 4.8. Added to the original 210 stars, they produce 450 stars across 100 ratings: exactly 4.5.
When your current average is below the target, the assumed average of new reviews must be higher than the target for a finite number of new reviews to reach it. New reviews averaging exactly the target bring you closer without closing the gap completely.
How long could it take?
A review-count estimate is not a deadline. For a rough planning scenario, divide the additional ratings required by an assumed number of new published reviews per month.
Thirty additional ratings at ten published reviews per month is about three months. That assumes the same pace, the specified ratings and no changes to existing reviews. Ten customers served or ten requests sent per month is not the same input.
Use your own observed pace when available and revisit the estimate as the rating and count change. Do not turn a calculator result into a quota for staff to obtain positive reviews.
What should you check when your Google rating has not changed?
First distinguish an unchanged displayed score from a missing review. A small change in the underlying average may not change a one-decimal display under a rounding model. The score may also not have updated yet: Google says an updated review score can take up to two weeks after someone leaves a new review. That is not a promise that every review will become publicly visible within two weeks. Check Google's review-score guidance.
Recheck the correct profile and current review count. If other ratings have been added, edited or removed, the old calculator inputs no longer describe the same situation. For a review that is absent rather than a score that is unchanged, follow our guide to Google reviews not showing up.
Can you reach an exact 5.0 average after a lower rating?
No finite number of additional five-star ratings can create an exact 5.000 average while any lower rating remains. The average approaches five. A displayed 5.0 may have a different meaning under a rounding model; it does not by itself prove that every rating is five stars.
Can you calculate a target with no existing reviews?
There is no established average yet. Zero reviews does not mean a zero-star rating. There is no current average for the tool to project from. Recalculate once you have published ratings, or use the worked examples to understand the arithmetic.
What to do after calculating your review goal
Use the result to understand the numbers, not to tell customers which rating to leave.
Address the experience behind the feedback. Look for specific concerns you can check and improve. Reply with a useful explanation or next step, and keep private customer details out of public responses. Our guide explains how to respond to Google reviews.
Make honest feedback easy. Invite genuine customers to share their experience without selecting only those likely to be positive. A direct Google review link or QR code can make the route clearer. Google's review-request guidance explains these options.
Keep the request neutral. Do not offer gifts, discounts or payment, pressure someone to give a particular rating, or set staff quotas for obtaining reviews. Google prohibits incentives and selectively soliciting positive feedback. Read Google's fake-engagement and rating-manipulation policy.
A low rating alone is not a reason to seek removal. Where a review actually violates policy, follow Google's reporting instructions. Reporting does not guarantee removal, and the calculator cannot remove reviews. For the wider profile, use our Google Business Profile optimization checklist.
Will reaching the target improve my Google ranking?
The calculator cannot predict that. Google describes local ranking through relevance, distance and prominence; reviews and positive ratings can help, but its guidance does not make a particular rating or review count a guaranteed position. See Google's local-ranking guidance.
A rating calculation also cannot establish how many enquiries or sales a business will receive. Keep the rating goal separate from how people find and choose your business.
Webbies works on websites, Google Business Profiles and search visibility. For help with that broader work, explore our SEO and local search services.
About this calculator
This is a manual planning tool by Webbies, not an official Google product. It uses the figures you enter and the assumptions shown with the result. It does not connect to your Business Profile, publish or remove reviews, or verify your live rating.
The formulas and worked examples are provided so you can follow the calculation. Examples are illustrative, not customer results. Recalculate when your inputs change, and treat any displayed-score simulation as a model rather than a guaranteed Google outcome.
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