Elo-MMR ratings go live on CodeChef!

I am new to CC. Can I know why this was necessary?
I mean, how CC was getting affected before this update?

By this what changes should be done in Provisional
Rating Means In Provisional
Rating rating they get is high (if they solve more problems) +ve delta as compare to Normal Rating

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I am new on CodeChef. I don’t know what is meant by provisional rating.

Just participate in 5 contests, and the question mark next to your rating will be removed.


I’m quite confused and disappointed with what’s been happening with the rating in Codechef. Yesterday after the STARTER50 my new rating on my profile was changed to 1913 from 1882. Today it changed to 1893 without participating in any contest. Even though ranked 11 globally my overall rating only changed 11 on profile! But I just checked the file ‘changes_after_starter50’ from the drive link. It shows the current elo_rating is 1802 and the previous elo_rating is 1836. I don’t get the math here. This whole transition is a mess.



After launching Elo-MMR, we got feedback from a lot of users about the sudden increase in ratings of new users, particularly in their first couple of contests. This was supposed to be a feature, but it had been a bit too much. So now, we have introduced a change, in which the weight of the first and second contests of a new user is changed to 60% and 80% of their old values, respectively. This leads to a slower increase in ratings of new users.

Along with Provisional Ratings, we hope this leads to a more robust rating eco-system.

This change has been applied for all users and their Elo-MMR rating recalculated from the beginning of time, and hence most users will see a change in their display ratings.

A comparison between the previous and current ratings (display ratings):

  • 31 users have an increase of more than 50
  • ~11700 users have an increase of between 0 and 50
  • ~465000 users have no change
  • 160 users have a decrease of more than 100 (70 of whom have been caught in cheating)
  • ~4000 users have a decrease of between 50 and 100
  • ~32000 users have a decrease of between 0 and 50.

You can find the entire list of users with their rating changes here.


can anybody explain why I got only 27+ rating in July Lunchtime 2022 Division 2 (Rated)
with 191 global rank
previous rating 1628

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@gouravcc1 - you can check out this thread.

it happened with me to with 191 globle rank in july lunchtime I got only 27+

I would say & support that codehef’s old rating system was good rather than current system . Because i think after giving a good performance than previous contest doesn’t brings any such change , even worst performance doesn’t brings any good decrement .
For 4* , 5* coders to get a gooding rating is now huge difficult than codeforces as well .


My codechef graph has changed…
Some time before I had participated in several competitions and most of my graph points were in 1400-1600(green) range but now the graph is showing those points to be above 1600(blue), Is this normal?
Can anyone explain why did this happen?

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@demonslah - so 2 things done in the last month

  • plagiarizers were removed and ratings recalculated for all users
  • ELO MMR introduced

This thread should give you an idea of th echanges.

That’s nice!!

:+1: :+1:

Ok, please provide an elaboration for a “-15” despite getting a rank of 684 in July Lunchtime Div 2. And a net “-34” in the hidden rating after securing a rank of 418 in Starters 50 ?

your hidden elo changes:
1664 after Starters 47
1701 after July Lunchtime 2022
1745 after Starters 50
1714 after Newbie Bonus recalculation

You had no negative elo changes from contests.

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I dunno why they reduced my rating and increased the ratings unnecessarily…why this is happening with me

Same happening with me sometimes increases and sometimes decreases auto

But i got increased in my ratings

Thanks for the info.
Was it affecting earlier in any cases when there was no provisional rating feature? @admin

I am asking this because it may make user to feel like “Hey! you are a new user and I don’t trust your skills so means I also don’t believe you solved these problems by yourself. Therefore as an empathy keep this provisional rating and don’t feel bad”.