Hello Everyone, me and thenewguy39 have been working on this CodeChef Rating Calculator/Predictor. So, if you do not want to wait for a day before rating changes get reflected you may give this a try.
Also we are still working on improving the accuracy. Presently we still have around 5-15% relative error for the changes. Feel free to go through the code and do suggest improvements.
P.S This is quite slow because CodeChef doesn’t have an API and we have to scrape each user in the rank-list once. So for a contest(except Div 2 Long Challenge) initial loading time is ~15mins even in a stable network. After that changes in rankings can be updated quite fast.