How is an average rating worked out?

Multiply each star level by how many ratings it received, add those products together, then divide by the total number of ratings. For example, 48 five-star, 22 four-star, 8 three-star, 3 two-star and 2 one-star ratings give a total of 360 stars across 83 ratings, an average of about 4.34 out of 5.

Why is the average rating a weighted mean?

Each star level is weighted by how many people chose it, so a level with more ratings pulls the average towards it. This is the same as a weighted average where the value is the star score and the weight is the number of ratings at that score.

What is a good average star rating?

There is no fixed threshold, but many shoppers treat 4.0 and above as strong and are wary below about 3.5. The number of ratings matters too, since a 5.0 from three reviews is far less reliable than a 4.4 from hundreds.

Average Rating Calculator

This average rating calculator turns a set of star review counts into a single average score out of 5. You enter how many ratings you received at each level, five star, four star, three star, two star and one star, and the calculator multiplies each level by its count, adds those products together, and divides by the total number of ratings to give the weighted average that most review sites display. It also shows your total number of ratings and the share of positive reviews, meaning the four and five star ratings, so you can see both the score and how much weight sits behind it. This is the same maths that Google, Trustpilot, app stores and product pages use to summarise many opinions in one figure, which is why a handful of low scores can drag an otherwise strong average down. Business owners use it to track reputation and to model how many new five star reviews would lift a score, shoppers use it to judge a product, and teachers and researchers use it to average survey responses on a rating scale. Remember that the count behind an average matters as much as the average itself, since a 5.0 from three reviews is far less reliable than a 4.4 from several hundred. Enter your counts below and the average updates as you type.

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4.34

average rating out of 5

Total ratings83

4 and 5 star share84.3%

Average rating = (sum of star value times count) / total ratings. Weighted mean, so busier levels pull the score. The count behind the average matters as much as the score itself.

How it works

Each star level is worth its number of stars, so a five star rating counts as 5 and a one star as 1. Multiply each level by how many ratings it received, add those totals, and divide by the total count of ratings. That weighted average is the score you see on review sites. Levels with more ratings carry more weight, so a large block of five star reviews lifts the average while a cluster of one star reviews pulls it down.

Worked example

You have 48 five-star, 22 four-star, 8 three-star, 3 two-star and 2 one-star ratings. The star total is (5 times 48) + (4 times 22) + (3 times 8) + (2 times 3) + (1 times 2), which is 240 + 88 + 24 + 6 + 2, or 360 stars. There are 83 ratings in all, so the average is 360 divided by 83, about 4.34 out of 5. The four and five star ratings are 70 of the 83, a positive share of 84.3%.

Related calculators

Average Calculator: mean of a list of numbers.
Weighted Average Calculator: values with custom weights.
Average Percentage Calculator: average several percentages.
Mean Median Mode Calculator: full set of averages.
Percentage Calculator: everyday percentage sums.

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