How many 5 star reviews are you short of?
The Asterias Google rating calculator counts the reviews between the rating you have and the one you want. Three figures to enter, and the answer appears as you type.
Your calculation
All three figures are on your Google listing.
The total shown on your listing, not just the ones with a comment.
Necessarily above your current rating.
To reach 4.5 out of 5, you need roughly
77new 5 star reviews
Between 64 and 89, depending on how Google rounds your current rating.
Your listing would then show 4.5, across 204 reviews.
To turn the result into a length of time.
The other milestones
What each step above your rating would take, using your own figures.
| Target | 5 star reviews needed |
|---|---|
| 4.5Your target | 77 |
| 4.7 | 212 |
| 4.8 | 381 |
| 4.9 | 889 |
What a single 1 star review costs you
One 1 star review would drop your rating to 4.18. Getting back to 4.2 would take 4 reviews at 5 stars.
That figure does not depend on the size of your listing: it is the same with thirty reviews and with three thousand. It depends only on your rating, and it climbs fast as that rating rises.
Free · No sign-up · Nothing is sent anywhere
How is a Google rating calculated?
Your rating is the average of every review you have, unweighted and never forgotten. A review from three years ago counts exactly as much as this morning’s.
The formula, in plain terms
(current rating × number of reviews + 5 × new reviews) ÷ (number of reviews + new reviews)The calculator does nothing more than solve that equation for your target. It all happens in your browser: none of your figures reach us.
The more reviews you have, the heavier the rating
A listing with thirty reviews moves in a few weeks. The same rating across a thousand reviews needs thirty times as many for the same tenth of a point. Which is the argument for starting early.
The last tenths are the expensive ones
Going from 3.5 to 4.0 and from 4.5 to 4.8 are not the same job. The higher the rating, the less a 5 star review adds to it, because there is less left to gain.
Nothing drops off
Google does not retire old reviews from the average. A bad patch two years ago still weighs on you today, and the only way to dilute it is to publish new reviews over it.
A 1 star review costs more than a 5 star review earns
At 4.2 it takes four perfect reviews to cancel a single one star review. At 4.8, it takes nineteen. Same arithmetic, seen from the other end.
How do you get the reviews you are missing?
The calculation gives you a number. Going and getting it is the part where a lot of businesses put themselves at risk without realising.
Ask, plainly
Most happy customers write nothing because nobody asked them to. A sentence at the end of a good visit, a QR code on the bill, a link in the confirmation message: nothing else changes how many reviews you receive as much.
Ask everyone, not just the happy ones
Screening customers so the link only reaches the satisfied ones has a name, review gating. It is against Google’s policies, and presenting reviews filtered that way as representative is a misleading practice under EU consumer law.
Answer the ones you already have
A customer who sees the owner reading and replying has one more reason to write. And your replies are public: they are read by everyone who looks at your listing afterwards, long after the reviewer has moved on.
Never buy reviews
A bought batch is recognisable by its pace and its phrasing, and the penalty runs from removing the reviews to suspending the listing. This page’s arithmetic only means something on real reviews: inflating the count does not lift a reputation, it gambles it.
Fix whatever produces the bad reviews
Adding perfect reviews while the cause keeps producing poor ones is bailing out a boat. The first job is knowing what keeps coming back, review after review, and that is not visible when you read them one at a time.
The step before
You know how many. Do you know why?
This calculator counts the reviews you are missing. It says nothing about what is losing them for you. Dr Phili, the other free Asterias tool, reads your listing’s public reviews and gives you a diagnosis: what keeps coming back as praise, what keeps coming back as criticism, and where to start.
Analyse my reviews for freeWhile your rating climbs
Want your reputation watched while you work on your rating?
Reaching a target is one thing, holding the pace is another. Asterias follows your new Google reviews, drafts replies in your own tone and alerts you on WhatsApp or Telegram whenever something needs your approval.
- Your new Google reviews, watched.
- Replies written in the tone of your business.
- Positive reviews get their reply on their own.
- Negative reviews never go out without your approval, by default.
Frequently asked questions
How do you calculate a Google average rating?
The rating Google shows is the plain arithmetic mean of every review received: the sum of the stars divided by the number of reviews. No review is weighted, and none drops out of the average over time. This page’s calculator solves that mean backwards, to say how many 5 star reviews you have to add to reach a rating you name.
How many 5 star reviews to go from 4.2 to 4.5?
It depends entirely on how many reviews you already have. With 50 reviews at 4.2 you need 30 five star reviews; with 127 reviews you need 77; with 500 reviews you need 300. That is the main lesson of the calculation: the same three tenths cost ten times more on an established listing than on a young one.
How long does it take to raise a Google rating?
The time needed is the number of missing reviews divided by the reviews you receive each month. A business receiving ten reviews a month that needs seventy of them will take seven months, and only if every one is perfect. Enter your monthly pace in the calculator to get that figure.
Can a negative Google review be deleted?
Only Google can remove a review, and only if it breaks its policies: hate speech, off-topic content, a conflict of interest, an obviously fake review. A negative but genuine review will not be removed, whatever you do. The realistic route is to dilute its effect with new reviews, and to answer it publicly.
Do old reviews still count towards the average?
Yes. Google does not expire reviews and does not weight them by date in the average it shows. A review from 2019 counts as much as one from today. How recent your reviews are does matter elsewhere: it shapes what a visitor reads first, and how much they trust the listing.
Can you reach 5.0 on Google?
Not once a single imperfect review exists on the listing. The average approaches 5.0 without ever reaching it, however many perfect reviews are added: that is why this calculator stops at 4.9 and refuses to give a number for 5.0 rather than showing an enormous one.
Does replying to reviews raise your rating?
Replying does not change the average: a reply is not a rating. It works elsewhere, and that matters just as much. An unhappy reviewer sometimes revises their own rating, future customers read the replies before choosing, and a listing where somebody answers attracts new reviews more readily.
Is this calculator really free?
Yes, and it asks for neither an account nor an email address. The calculation runs in your browser: your rating, your review count and your target are sent nowhere and stored nowhere. It is published by Asterias, which separately sells a service that manages review replies.