Google Review Calculator
To raise a Google rating from R to T when you already have C reviews, you need C × (T − R) ÷ (5 − T) new 5-star reviews, rounded up. A business at 4.2 stars with 80 reviews needs 48 five-star reviews to reach 4.5. Google’s displayed rating is the plain average of every published rating, shown to one decimal — so once you know your published review count, the arithmetic is exact.
How many 5-star reviews do I need?
Enter the rating on your Google Business Profile today, how many reviews produced it, and the rating you want. The answer is the number of consecutive 5-star reviews that gets you there — plus what your average and your visible rating become when they land.
5-star reviews needed
48
That takes you from 4.2 to a displayed 4.5.
New review total
128
Exact new average
4.5
Google would show 4.5
Next visible rating step
4.3
6 five-star reviews away
Rating shown today
4.2
80 published reviews
If you got one 1-star review tomorrow
Your average becomes 4.16, shown as 4.2. The rating people see does not move.
Your displayed rating is rounded to one decimal, so the true average behind it can sit anywhere in a 0.1 band. Treat the answer as accurate to within a review or two.
Reviews needed for 25 common situations
Find your rating jump on the left and your review count across the top. Every figure is the exact minimum, rounded up. Nothing here needs JavaScript, so you can print it, quote it, or read it on a bad connection.
| Rating jump | 25 reviews | 50 reviews | 100 reviews | 250 reviews | 500 reviews |
|---|---|---|---|---|---|
| 3.5 to 4.0 | 13 | 25 | 50 | 125 | 250 |
| 4.0 to 4.5 | 25 | 50 | 100 | 250 | 500 |
| 4.2 to 4.5 | 15 | 30 | 60 | 150 | 300 |
| 4.5 to 4.8 | 38 | 75 | 150 | 375 | 750 |
| 4.7 to 4.9 | 50 | 100 | 200 | 500 | 1,000 |
The pattern is the whole lesson: the same 0.3-star jump costs two and a half times as much starting from 4.5 as it does from 4.2, because the gap between a 5-star review and your target is what does the work.
How this Google review calculator works
Your Google rating is a mean. Every review contributes its own star value to a total, and the total is divided by the number of reviews. Adding 5-star reviews raises the total faster than it raises the count, which is why the average climbs — and why it climbs more slowly the higher you already sit.
The formula
reviews needed = ⌈ C × (T − R) ÷ (5 − T) ⌉
- C — reviews published on your profile now
- R — the rating those reviews produce today
- T — the rating you want
- ⌈ ⌉ — round up: a partial review does not exist
Where the formula comes from
Start from the definition of the average you want, then solve for the only unknown. With n new 5-star reviews:
- T = (C×R + 5n) ÷ (C + n) — the average you are aiming at
- T×(C + n) = C×R + 5n — multiply both sides
- T×C + T×n − 5n = C×R — collect the n terms
- n×(5 − T) = C×(T − R) — factor out n
- n = C×(T − R) ÷ (5 − T) — divide, then round up
Worked, with real numbers
A business has 80 reviews averaging 4.2 and wants 4.5.
- 80 × (4.5 − 4.2) ÷ (5 − 4.5) = 80 × 0.3 ÷ 0.5 = 48
- Check it: 80 × 4.2 = 336 stars today. Add 48 × 5 = 240 more, for 576 stars across 128 reviews.
- 576 ÷ 128 = 4.50 exactly.
What Google’s own documentation says
Google Business Profile Help, Understand review scores for local places & businesses, states the review score is the average of all ratings published on Google for that place or business
. The same page warns that after a new review is left, it may take up to 2 weeks to get an updated review score
. Read 13 August 2026.
Two things follow, and both matter for this calculator. Only published ratings count, so reviews Google filtered before publishing were never in your average to begin with. And the arithmetic is a plain mean — no documented weighting by review age, length, or who wrote it.
Worth checking yourself. On 13 August 2026 we read the FAQ sections of the calculators ranking on page one for this term. At least one prints the average-rating formula upside down — total reviews divided by total stars — while the prose beside it describes the calculation correctly. Inverted, the formula always returns 1 ÷ your rating, so every 4.2-star business comes out as 0.24 regardless of review count. That is the tell.
Why your Google rating doesn’t match your own math
If you add up your stars and get a different number than Google shows, three things explain almost every case: reviews filtered out before publication, which never entered the average; the rounding to one decimal; and the update lag Google documents as up to two weeks.
None of them changes the formula — they change which reviews are in it and when you see the result. We took that apart in detail, with the primary sources, in how Google calculates your rating. If your question is a target rather than a mechanism, read how many Google reviews do you need instead.
How many 5-star reviews cancel out one 1-star?
Enough to pull the average back to where it started, which works out at (R − 1) ÷ (5 − R), rounded up. The striking part is what is missing from that expression: your review count. A 1-star costs the same number of 5-star reviews to undo whether you have 20 reviews or 20,000.
| Your rating | 5-star reviews to undo one 1-star |
|---|---|
| 4.0 | 3 |
| 4.2 | 4 |
| 4.5 | 7 |
| 4.7 | 13 |
| 4.9 | 39 |
What changes is how much it hurt in the first place, and that is the argument for volume. Two 1-star reviews drop a 4.9 profile with 30 reviews to a displayed 4.7; the same two reviews leave a 4.9 profile with 300 reviews still showing 4.9. The practical answer is a steady flow of reviews rather than a rescue mission after a bad one — which starts with knowing how to get customers to leave reviews.
What if the target is impossible?
A target of 5.0 cannot be reached by adding reviews. Put T = 5 into the formula and the denominator becomes zero: once a single rating below 5 is published, more 5-star reviews move the average closer to 5 forever without arriving. This calculator says so rather than printing a number.
There is a useful answer underneath the impossible one. Google shows the score to one decimal place, so an average of 4.95 displays as 5.0 — and 4.95 is reachable. Enter 5.0 as your target and the tool tells you how many 5-star reviews it takes to cross that line instead.
The same rounding works in your favour lower down the scale. You never need to reach 4.5 to be shown as 4.5; you need 4.45. That is often several reviews of difference, and it is why the tool reports the next visible step separately from the exact average.
Frequently asked questions.
The questions people search after running the numbers.
Visit support centerWhat is the Google review calculator formula?
Reviews needed = your review count x (target rating - current rating), divided by (5 - target rating), rounded up. With 80 reviews at 4.2 stars and a 4.5 target: 80 x 0.3 / 0.5 = 48. Always round up, because a partial review does not exist.
How many reviews do I need to raise my rating by 0.1?
It depends on how many reviews you have and how high you already sit. At 4.2 stars with 100 reviews, 7 five-star reviews move the displayed rating to 4.3. At 4.7 stars with 100 reviews, the next tenth costs 20. Every step up the scale costs more than the one before it.
Do 4-star reviews raise my Google rating?
Only if your average is below 4.0. Every new rating pulls the average toward its own value, so a 4-star review lifts a 3.6 profile and drags a 4.6 profile down. Above 4.0, only 5-star reviews move you up.
Can you get a 5.0 rating on Google?
Only if every published rating is a 5. Once one lower rating is in, no number of 5-star reviews returns the true average to exactly 5.0 — it only gets closer. Google shows one decimal place, so an average of 4.95 or higher displays as 5.0.
Does replying to reviews change my star rating?
No. The score averages the ratings customers publish, so replies, photos, and review length never enter the arithmetic. Replying is still worth doing, because everyone reading that review sees your answer, but it will not move the number.
Why does the calculator say I need more reviews than I expected?
Two reasons. Each new review adds to the bottom of the fraction as well as the top, so the finish line moves while you run at it. And the closer your target sits to 5.0, the smaller the gap a 5-star review can close, which is why 4.5 to 4.8 costs far more than 4.0 to 4.3 at the same review count.
Is this Google review calculator free?
Yes. No signup, no email address, no limit on how many times you run it. The arithmetic happens in your browser, so the numbers you type stay on your device.
Ready to turn that number into reviews?
Knowing the target is the easy part. A Krofile Review Card turns a tap or a QR scan into a Google review, so the count actually moves. Free to start.