A single one-star review can visibly drag down a good rating. How many five-star reviews it takes to make up for it can be calculated exactly, and the answer surprises many business owners: at a 4.5 average, it is seven. This guide shows the formula behind it, works through examples step by step and provides lookup tables. It also covers what the numbers mean for your review strategy and why some platforms calculate differently from Google.
Quick answer: how many five-star reviews offset a weak review
The number depends only on the average you want to keep, not on how many reviews you already have. The table shows how many new five-star reviews you need to bring your average back to where it was after a weaker review. The columns stand for the stars of that weaker review:
| Average | 1 star | 2 stars | 3 stars | 4 stars |
|---|---|---|---|---|
| 4.0 | 3 | 2 | 1 | 0 |
| 4.3 | 5 | 4 | 2 | 1 |
| 4.5 | 7 | 5 | 3 | 1 |
| 4.6 | 9 | 7 | 4 | 2 |
| 4.7 | 13 | 9 | 6 | 3 |
| 4.8 | 19 | 14 | 9 | 4 |
| 4.9 | 39 | 29 | 19 | 9 |
How to read it: if your average is 4.5 and a one-star review comes in, you need seven five-star reviews to get back to 4.5. At 4.8, it takes 19. The values are rounded up, because there is no such thing as half a review.
Why one bad review weighs so much
Your average is the total of all stars divided by the number of reviews. Every new review pulls it in its own direction, and the further the review sits from the average, the harder it pulls.
At a 4.5 average, a one-star review sits 3.5 stars below. A five-star review sits only 0.5 stars above. To balance the gap below, you need 3.5 ÷ 0.5 = 7 reviews above.
This leads to the most important rule in this article: the better your average, the more each outlier costs. At 4.0, every five-star review still has a full star of headroom; at 4.8, only 0.2. That is why the cost of offsetting rises so steeply toward the top.
The general formula for a single weaker review is:
Offset = (your average − stars of the review) ÷ (5 − your average), rounded up.
A four-star review also lowers any average above 4.0, by the way. At 4.6, it takes two five-star reviews to offset it. That is no reason to worry, but it explains why a very high average fluctuates even when nearly all reviews are good.
The formula for your target: how many five-star reviews do I need?
If you want to raise your average rather than just hold it, factor in the number of reviews you already have:
Five-star reviews needed = number of reviews × (target − current average) ÷ (5 − target), rounded up.
A step-by-step example: a business has 40 reviews averaging 4.2 and wants to reach 4.5.
- Gap to the target: 4.5 − 4.2 = 0.3
- Times the number of reviews: 40 × 0.3 = 12. That is how many stars today's total falls short of the target.
- Divided by how far a five-star review sits above the target: 5 − 4.5 = 0.5, so 12 ÷ 0.5 = 24.
The business needs 24 more five-star reviews, assuming no weaker review comes in meanwhile. The check: today the total is 40 × 4.2 = 168 stars. Adding 24 × 5 = 120 stars gives 288 stars across 64 reviews, and 288 ÷ 64 is exactly 4.5.
Lookup tables for common targets
The tables below show how many five-star reviews you need for three common targets. The columns stand for the number of reviews you have today. All values assume that only five-star reviews come in until you reach the target, so in practice you will need a few more.
Target: 4.0 stars
| Average today | with 20 | with 50 | with 100 | with 200 |
|---|---|---|---|---|
| 3.2 | 16 | 40 | 80 | 160 |
| 3.5 | 10 | 25 | 50 | 100 |
| 3.8 | 4 | 10 | 20 | 40 |
Target: 4.5 stars
| Average today | with 20 | with 50 | with 100 | with 200 |
|---|---|---|---|---|
| 3.8 | 28 | 70 | 140 | 280 |
| 4.0 | 20 | 50 | 100 | 200 |
| 4.2 | 12 | 30 | 60 | 120 |
| 4.4 | 4 | 10 | 20 | 40 |
Target: 4.8 stars
| Average today | with 20 | with 50 | with 100 | with 200 |
|---|---|---|---|---|
| 4.4 | 40 | 100 | 200 | 400 |
| 4.5 | 30 | 75 | 150 | 300 |
| 4.6 | 20 | 50 | 100 | 200 |
| 4.7 | 10 | 25 | 50 | 100 |
Two patterns stand out. First, the requirement grows in proportion to your number of reviews: twice as many reviews means twice as many new ones for the same jump. Second, every tenth of a star gets more expensive. Going from 4.4 to 4.5 with 100 reviews takes 20 new five-star reviews; going from 4.7 to 4.8 takes 50.
Volume protects you: how much a single review moves the average
The same math has an upside. The more reviews you have, the less any single one moves your average. The table shows what a new one-star review does to an average of exactly 4.5:
| Reviews so far | Average afterwards | Change |
|---|---|---|
| 10 | 4.18 | −0.32 |
| 20 | 4.33 | −0.17 |
| 50 | 4.43 | −0.07 |
| 100 | 4.47 | −0.03 |
| 200 | 4.48 | −0.02 |
With ten reviews, a single one-star review costs about a third of a star. With 100 reviews, the same review moves the average by only three hundredths.
The most effective insurance against outliers is therefore not a perfect average but a steady flow of genuine reviews. How to ask customers in a way that gets answers is covered in the guide to review requests.
Watch the rounding: calculate with the exact total
Google displays your average with one decimal place. That is too coarse for planning, because even a few hundredths make a difference. An example with 40 reviews: between an exact average of 4.15 and one of 4.25 lie four stars of total, 166 instead of 170. For a 4.5 target, that means 28 instead of 20 five-star reviews.
So work out the exact total from your star distribution: the number of reviews at each level times that level's stars, all added up. A tool that collects your reviews shows the distribution at a glance.
What counts is also what Google actually publishes. Removed or withheld reviews are missing from both the count and the average, while star ratings without text count in full. Plan with a buffer in case a weaker review comes in along the way.
Does the math also apply to other platforms?
For Google, you can plan with the simple average. Some platforms work differently: their score is not a simple average. Newer reviews count more than older ones there, and while a profile has only a few reviews, a fixed baseline pulls the score toward the middle. On such platforms, the formula in this article therefore shows the direction, not the exact number.
Two consequences still follow. An old one-star review loses weight over time there. And a steady stream of new reviews has more effect there than a one-off push whose reviews will also lose weight later.
Other platforms may have their own rules and, for example, only count reviews from a certain period. Check each platform's help pages before you set a target. How to keep several platforms in view at once is covered in the article on multichannel reputation.
What the numbers mean for your review strategy
Six rules for everyday practice follow from the math:
- Ask continuously instead of collecting once. Many reviews make your average robust. A fixed routine in which every customer is asked after a purchase or job does more than a one-off campaign.
- Ask every customer, not just the happy ones. Google's policies prohibit selectively soliciting positive reviews. Ask for an honest opinion. Email requests also have to follow the rules in the article on GDPR-compliant review requests.
- Reply to every bad review. A good reply does not change the stars, but it changes how readers interpret the review. If you solve the problem, you also give the person a reason to reconsider their review; they can change it themselves at any time. You will find wording for this in the templates for negative reviews.
- Report reviews that break the rules. If Google removes a one-star review that violates its policies, your average returns to where it was. At a 4.5 average, that saves you seven five-star reviews. How reporting works and when it has a chance of success is explained in the guide to removing Google reviews. Genuine criticism stays up, and rightly so.
- Fix the causes. If complaints about the same issue keep coming, every further one-star review costs another seven five-star reviews at a 4.5 average. A fixed problem prevents that cost before it arises.
- Match your target to your customer volume. Work out how many reviews your target costs and compare that with the number of customers you can ask in the same period. That turns a wish into a plan.
Keeping your average in view
A calculation is only as good as the numbers that go into it. In RateGate, the Analytics page shows average rating, reply rate, star distribution and history, for all locations or each one individually. That way you can see whether your request routine actually moves the average.
New reviews from Google, Trusted Shops and ProvenExpert arrive in one shared inbox, so a one-star review stands out instead of getting lost in one of several portals. If you use the Automatic replies feature from the Silver plan, you decide from how many stars RateGate replies automatically. Reviews below that stay in the inbox for manual review, so critical cases get a personal reply.
Frequently asked questions
How many 5-star reviews do I need to offset a 1-star review?
It depends on your average. At 4.0 it takes three, at 4.5 seven, and at 4.8 as many as 19 five-star reviews. The formula is (average − 1) ÷ (5 − average), rounded up.
How does Google calculate my average rating?
For planning, you can use the simple average of all published star ratings: the total of all stars divided by the number of reviews. Google displays the result with one decimal place. Small differences from your own calculation can come from rounding or from reviews that Google has removed or does not show.
Do ratings without text count?
Yes. On Google, star ratings without text count toward both the number of reviews and the average. Mathematically, a one-star rating without text weighs exactly as much as one with a detailed explanation.
At what number of reviews is my average stable?
There is no fixed threshold, but the effect of a single review shrinks with every additional one. At a 4.5 average, a one-star review costs about 0.32 stars with 10 reviews and only about 0.03 with 100.
Why is my average dropping even though nearly all my reviews are good?
Because any review below your current average lowers it, including a four-star review. At a 4.6 average, it takes two five-star reviews to offset a single four-star review. A very high average therefore fluctuates even with small deviations.
Is it worth having a bad review removed?
Only if it violates the platform's policies, for example because there was never any customer contact. In that case, removal restores your previous average. Genuine criticism cannot be removed; what helps here is a factual public reply.
Conclusion
At a 4.5 average, a one-star review costs seven five-star reviews; at 4.8, it costs 19. The formula behind it is simple, and it leads to a clear strategy: ask for reviews continuously and honestly, reply to every criticism, report policy violations and fix recurring causes. The more genuine reviews you have, the less a single one can hurt you.
RateGate helps you keep the numbers in view: with one inbox for Google, Trusted Shops and ProvenExpert, and with analytics on average rating, star distribution and history for each location. The features page gives an overview.
