Free tool
Google Rating Calculator
Find out how many 5-star reviews you need to raise your Google rating to 4.5, 4.7 or any target — and what one bad review does to your average.
5-star reviews needed to reach 4.5★
29
Assuming every new review is 5★.
One new 1-star review would take you to
4.13★
You'd need 4 five-star reviews to get back to 4.2★.
Google shows the average rounded to one decimal; its exact calculation isn't published, so treat this as a close estimate.
The maths behind your star rating
Your Google rating is (approximately) the average of all review stars. Each new 5-star review pulls the average up a little; how much depends on how many reviews you already have. That's why review count protects you: a business with 300 reviews barely notices one unfair 1-star review.
Worked example
A salon has 48 reviews at 4.2★ and wants 4.5★. Needed = 48 × (4.5 − 4.2) ÷ (5 − 4.5) = 28.8 → 29 five-star reviews. At 8 reviews a month, that's under four months — see review velocity.
Get there the right way
- Ask every customer — staff scripts
- Put a review QR at the counter
- Fix the issues that cause low ratings, and reply to every review
Frequently asked questions
How many 5-star reviews do I need to get a 4.5 rating?
It depends on your current average and count. Formula: needed = reviews × (target − current) ÷ (5 − target). For 48 reviews at 4.2, you need 29 five-star reviews to reach 4.5.
How much does one 1-star review hurt?
With few reviews, a lot. At 10 reviews averaging 4.8, one 1-star drops you to about 4.45. At 300 reviews it barely moves.
Does Google round the rating?
Google displays one decimal place. Its exact calculation isn't published, so treat results as close estimates.
Can I buy reviews to reach my target faster?
No. Fake or incentivised reviews break Google's policies and get removed — often with penalties.