This page explains how Fredrik Persson (USATT# 218929)'s rating went from 1258 to 1287 at the LATTA Butterfly Open December 2021 held on 4 Dec 2021 - 4 Dec 2021. The links below take you to pages that describe various aspects of the rating processor.

The rating processor goes through 4 passes in order. The links take you to pages that provide detailed explanations of the calculations during each of the 4 passes.