The average rating calculator takes a number of votes for each rating (1 star, 2 stars, 3 stars, 4 stars, 5 stars) and gives you the mean rating. This is an example of taking the weighted average, where the number of votes for each category are weighted by their score (i.e., 3 votes for 5 stars have a weight of 15, 6 votes for 4 stars have a weight of 24, etc.).
Keep reading to learn what is the star rating system, the difference between a star classification and an average star rating, and how to calculate the star rating for any combination of votes.