Google Review Calculator: How Many 5-Star Reviews You Need
Enter your current rating, review count and the rating you want. You get the number of 5-star reviews it takes, a safer number that allows for some lower ratings, and a pace per month.
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How the math works
Google says the review score "is the average of all ratings published on Google for that place or business" (Google Business Profile Help, checked 2026-10-08). So: add up every star rating and divide by the number of reviews. To lift an average of R over N reviews to a target T with 5-star reviews only, you need N x (T - R) / (5 - T) new reviews, rounded up.
Worked example: 50 reviews at 4.2, aiming for 4.5. That is 50 x 0.3 / 0.5 = 30 five-star reviews. Check it: (4.2 x 50 + 5 x 30) / 80 = 4.5.
Your profile shows the rating with one decimal, and Google doesn't say how it rounds. A shown 4.2 could sit anywhere from about 4.15 to just under 4.3. The safer number starts from the low end, so it never comes up short.
Not every new review will be 5 stars. The planning number assumes a share of new reviews come in lower (10% at 3 stars unless you change it). That makes new reviews average 4.8 instead of 5, and the target takes more reviews to reach. If your new reviews would average at or below your target, the target can't be reached that way, and the calculator says so.
Google also says that after a new review, "it may take up to 2 weeks to get an updated review score", so expect your shown rating to lag behind the reviews coming in.
The competitor check adds two numbers: how many reviews put you one past their count, and how many lift your shown rating one tenth above theirs (or to 4.9 if they already show 4.9 or 5.0). It assumes their numbers stay still, which they won't, so treat it as a floor.
Getting there without breaking Google's or the FTC's rules
Google and the FTC both have rules about how you get reviews. Breaking them can get reviews removed from your profile, and fake or bought reviews can bring FTC penalties. Here is what they say, quoted.
"Offer incentives – such as payment, discounts, free goods and/or services - in exchange for posting any review or revision or removal of a negative review."
Listed as not allowed. No discounts, gift cards or freebies for a Google review, even for an honest one.
"Discourage or prohibit negative reviews, or selectively solicit positive reviews from customers"
Listed as not allowed. Ask every customer, not only the happy ones. Screening customers first and sending only the happy ones to Google (review gating) is the selective asking this rules out.
"Merchants requesting that staff solicit a certain number of reviews"
Listed as an example of what's not allowed. Set a habit of asking, not a review quota for your team.
"It is an unfair or deceptive act or practice and a violation of this part for a business to provide compensation or other incentives in exchange for, or conditioned expressly or by implication on, the writing or creation of consumer reviews expressing a particular sentiment, whether positive or negative ..."
Paying or rewarding people for positive reviews is illegal under federal rule. Google goes further and bans any incentive for a review.
"It is an unfair or deceptive act or practice and a violation of this part for a business to write, create, or sell a consumer review, consumer testimonial, or celebrity testimonial that materially misrepresents, expressly or by implication: (1) That the reviewer or testimonialist exists ..."
No fake reviewers, including reviews written by AI. The FTC's announcement (August 14, 2024) names AI-generated fake reviews as covered.
A simple plan for asking
- Ask every customer when the job is done, the same way each time. A short text or email with your review link works, and Google says you can ask customers to visit a Google link or scan a QR code.
- Make it a routine, not a campaign. Your monthly pace above is easier to hit as a steady habit than in a single push.
- Divide the monthly pace by the customers you serve in a month. That is the share of customers who would need to leave a review. If it looks out of reach, give yourself more months.
- Reply to reviews, the good and the bad. Google's own tips page says replies show you value feedback and that positive reviews and helpful replies can help your business stand out.
- Google's tips for local ranking say more reviews and positive ratings can help your business's local ranking. A steady habit is also easier to keep up than a one-time push.
Questions
How does Google calculate my star rating?
Google's help page says the review score is the average of all ratings published on Google for your business, on a scale of 1 to 5 stars. It also says the score may take up to 2 weeks to update after a new review. This calculator uses that same average.
How many 5-star reviews do I need to get to 4.5?
It depends on where you start. With 50 reviews at 4.2, it is 30 if every new review is 5 stars. With 100 reviews at 4.2, it is 60. The calculator's main number is higher because it also allows for rounding and some lower ratings. Put your own numbers in the calculator; the formula is N x (T - R) / (5 - T), rounded up.
Can I get a perfect 5.0 rating?
Only if every review you have is 5 stars. Once any review is lower, the average can get very close to 5 but never reach it, so the calculator asks you to pick 4.9 or lower in that case.
Why is the safer number higher than the simple answer?
Your profile shows one decimal. A shown 4.2 might really be a little lower, like 4.16, so the safer number starts from the lowest true average that could be behind what you see.
Can I offer a discount or a gift card for a Google review?
No. Google's content policy lists offering incentives, including payment, discounts and free goods or services, in exchange for posting a review as not allowed. Rewarding reviews of a particular sentiment also breaks the FTC's 2024 rule.
Is it okay to only ask happy customers?
No. Google's policy lists selectively soliciting positive reviews from customers as not allowed. Ask everyone the same way and reply to what comes in.
Does this calculator look up my Google profile?
No. You type the numbers from your Google Business Profile, and the math runs in your browser. Nothing is sent to us or to Google.
Sources
- Google Business Profile Help: Understand review scores for local places & businesses (checked 2026-10-08)
- Google Maps user contributed content policy: Prohibited & restricted content (Fake engagement; Rating manipulation) (checked 2026-10-08)
- Google Business Profile Help: Tips to get more reviews (checked 2026-10-08)
- Google Business Profile Help: Tips to improve your local ranking on Google (checked 2026-10-08)
- Federal Register, FR Doc. 2024-18519 (August 22, 2024): Trade Regulation Rule on the Use of Consumer Reviews and Testimonials, 16 CFR Part 465 (checked 2026-10-08)
- FTC press release, August 14, 2024: Federal Trade Commission Announces Final Rule Banning Fake Reviews and Testimonials (checked 2026-10-08)
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