Had a question about CodeChef Rating Formula


I just saw the Codechef rating mechanism, It seems like another CP Question, Link to Rating Mechanism

It would be of great help if a veteran CodeChef User or a person who has understood this rating mechanism could explain how things work and how we can predict the rating change.

Based on your current rating and strength of participants in the contest, Codechef will calculate a expected score for you. If you perform better than it, then your rating increases else it decreases.

Thank You for your reply Amey,

I wish to know how it’s judged that we have performed better than their expectations, In simple terms, What’s their expectation?

Expected ranking

Do they consider the percentile?
If the percentile > percentile in previous content

  • Rating increases.
  • Rating decreases.

Your question, as well as the numbers that actually go behind it, is answered in the page you linked

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If you want to think in terms of percentile, then you cannot compare percentiles in previous contests with percentile in the current contest, since the strength of participants will vary over contests. This means a 80 percentile in a easy contest is not same as a 80 percentile in a difficult contest. You can read about Elo Rating System in general to understand the idea.