How these numbers are computed

The rating model

Your Google rating is the arithmetic mean of your star ratings, displayed rounded to one decimal place. Two consequences drive everything else:

• Rounding thresholds. A rating displays as T once the true mean reaches T − 0.05. An average of 4.75 displays as 4.8; an average of 4.7499 displays as 4.7.
• Weight of history. Every existing review anchors the mean, so the 5-star reviews needed to cross a threshold scale with your current review count.

"Reviews needed" is the smallest whole number x such that (current total stars + 5x) ÷ (current review count + x) meets the target's rounding threshold. The implementation works entirely in scaled integers — no floating-point rounding — and is covered by property tests that verify, for hundreds of star distributions, that x − 1 reviews miss the target and x hit it.

Assumptions in the published tables

The rating guide pages model a business whose true mean is exactly the displayed value (a page about 4.3 assumes an average of exactly 4.30). Real businesses sit somewhere inside the rounding window, so their real numbers differ slightly — that's what the calculator resolves using your actual per-star counts. "Consecutive 5-star reviews" means no new lower-rated reviews arrive in between; mixed incoming reviews raise the required count.

We model the displayed rating as a simple rounded mean. Google states that its displayed score may not be a strict arithmetic average in all cases (spam filtering and other signals can intervene), but the rounded mean of visible reviews is the observable behaviour the tool tracks, and it matches live profiles closely.

Where the review data comes from

When you search a business in the calculator, we fetch its publicly visible Google Business Profile data — name, address, overall rating, review count, and the per-star breakdown — through a commercial data provider. We don't access private data, review text, or reviewer identities, and we cache results briefly at the edge so repeat lookups don't re-query the source.

The per-star breakdown is reconciled against the profile's total review count before we use it; lookups that can't be reconciled are rejected rather than shown.

Who runs this site

ReviewScoreCalculator is built and maintained by Relentlabs, a digital agency specialising in review and reputation management for local businesses. The tool is free and requires no signup; it exists because "how many 5-star reviews do I need?" deserves an exact answer, not a guess.