This handy chess rating calculator app can calculate the expected score, rating change and performance rating of your chess games.

It uses FIDEs official rating rules and includes the new 400 rating difference rule used in the ELO rating system. You can enter game data and the rating calculations are automatically saved, so you do not need to re-enter them if you add further games later on. You can save a rating list as a tournament to keep track of your results and improvements from tournament to tournament (this last feature is only available in the full version)

Furthermore, various k-factors are supported - also non-FIDE k-factors used by many national chess federations, so you can use this app for local tournaments as well.