The way star rating is calculated is
(( #5 star reviews * 5 ) + ( #4 star reviews * 4 ) + ( #3 star reviews * 3 ) + ( #2 star reviews * 2 ) + ( #1 star reviews * 1 ) ) / Total number of reviews.
Let us say below is the review distribution for a brand.
5 stars: 388 reviews
4 stars: 31 reviews
3 stars: 11 reviews
2 stars: 34 reviews
1 star: 582 reviews
Star rating - (388x5 + 31x4 + 11x3 + 34x2 + 582x1) / 1046 = 2.626
On CX Reputation platform the star rating shown would be - 2.6. This calculation is applicable to all the other integrations as well.
Trustpilot ratings are different than the standard ratings calculation. Check the
link.