How this instrument works
Every product page, app store listing, and review site displays a single average star rating, but that number is a weighted average, not a plain one. It's not simply (1+2+3+4+5)/5 = 3 regardless of the data — each star level counts once for every rating it received, so a product with a thousand 5-star reviews and one 1-star review sits very close to 5.0, not near the midpoint of the scale. The weighted-average formula multiplies each star value by how many people gave it, adds those products together, and divides by the total number of ratings.
This structure matters because two products can show wildly different totals from similar-looking review counts. A product with 50 reviews split evenly across 1 through 5 stars averages exactly 3.0, while a product with the same 50 reviews concentrated at 4 and 5 stars, with only a few 1s and 2s, can easily average well above 4.0 — the shape of the distribution, not just the review count, drives the final number.
This calculator also reports the total number of ratings alongside the average, since a 4.8 average built from 5 reviews and a 4.8 average built from 5,000 reviews represent very different levels of confidence, even though the headline number looks identical. The average alone never tells you how many people actually voted.
- Enter how many people gave each star level into 1-star ratings through 5-star ratings.
- Read Average (weighted) rating beneath — the true star average across every rating entered.
- Check Total number of ratings alongside it to see how many reviews the average is built from.
- Leave a star level at 0 if no one gave that rating — the calculator only needs at least one rating entered somewhere.
- Compare two products by entering each one's breakdown separately; the average alone can hide very different underlying distributions.
Worked example — 50 reviews of a mobile app
A mobile app has collected 50 reviews: 2 one-star, 3 two-star, 5 three-star, 10 four-star, and 30 five-star. Enter 2, 3, 5, 10, and 30 into the five rating fields. Total number of ratings reads 2+3+5+10+30 = 50.
The weighted sum is (1×2)+(2×3)+(3×5)+(4×10)+(5×30) = 2+6+15+40+150 = 213. Dividing by the 50 total ratings gives Average (weighted) rating = 213/50 = 4.26 exactly — a strong score driven by the large block of 5-star reviews, even though 5 people rated it 3 stars or lower.
Questions
Why isn't the star rating just the average of 1, 2, 3, 4, and 5?
Because that would ignore how many people actually chose each rating — it would treat a single 1-star review the same as a thousand of them. A weighted average multiplies each star level by the number of people who gave it, so star levels with more votes pull the overall average toward them proportionally more. That's why a product can show a 4.5+ average even though every integer from 1 to 5 appears somewhere in its review breakdown.
Can two products have the same average with very different review breakdowns?
Yes, easily. Five ratings of 1, 1, 5, 5, 3 average to 3.0, and so do five ratings that are all exactly 3 — the same weighted average can come from a polarized split or from universal agreement. If you need to distinguish those cases, look at the full breakdown (or a spread measure like standard deviation) rather than the average alone.
Does the total number of ratings affect the average itself?
Not directly — doubling every rating count (say, from 2/3/5/10/30 to 4/6/10/20/60) leaves the weighted average exactly unchanged, since both the numerator and denominator double together. What the total does affect is how much confidence to place in that average: a 4.26 built from 50 ratings is a more stable estimate of general sentiment than the same 4.26 built from 5.
What if I only have ratings at one or two star levels?
That's fine — enter 0 for any star level with no ratings, and the calculator still computes correctly from whichever levels have entries. If every rating you have sits at, say, 5 stars, the average will simply come out to exactly 5.0, since there's no lower rating pulling it down.
Is this the same calculation platforms like app stores or review sites use?
Yes — this is the standard weighted-arithmetic-mean formula behind the single star number shown on most review platforms, applied to a 1-through-5 star scale. Some platforms layer additional adjustments on top (recency weighting, verified-purchase weighting, fraud filtering), but the core weighted average is this same calculation.