This is the question every owner asks first and almost nobody answers with a number, because the honest answer is arithmetic rather than advice. A rating is a weighted average, and the reviews already sitting on the profile push back against every new one. The worksheet on this site does the sum; here is what it is doing and why the answer surprises people.
Why a rating is slow to move
A rating is the mean of every review ever left. A business on 4.1 with sixty reviews has a total of 246 stars, and each new five star review adds five to the total and one to the count. Getting to 4.5 means the mean has to rise by 0.4 across a base that grows only one review at a time, which is why the first ten feel like nothing. The more reviews you already have, the more inertia works against you, which is the opposite of what most owners assume.
The number of asks behind the number of reviews
Not everybody asked leaves a review. A well timed text to a happy customer converts far better than an email a week later, and the difference between those two response rates changes the answer by a factor of several. The worksheet takes your own response rate, or a conservative guess if you have never measured one, and turns the reviews you need into the customers you have to ask.
What to do with the answer
Usually one of two things. Either the number of asks is achievable within your customer volume, in which case the job is building the habit of asking every one of them. Or it is not, and the honest conversation is about how long it will take rather than whether it will work. Both are better than the vague promise of improvement that this category normally sells.
Questions people ask about how many google reviews do i need
Do older reviews stop counting?
They keep counting in the average. Recency affects what a reader notices and how a platform may rank you, but the number on the profile is the mean of everything.
Is it faster to remove a bad review than earn good ones?
Removal only works where a review breaks the platform's rules, which is rare and slow. For everything else the arithmetic above is the only route, and it is why asking every customer beats any clever tactic.
What response rate should I assume?
Measure yours rather than assume, and if you cannot, assume something conservative and be pleasantly surprised. Optimistic response rates are how these projections end up wrong by months.