# Exact explanation of the calculation of the rank

The OGS site is lacking an exact calculation of the rank.
I only find this explanation in the help:

which only refer to wikipedia. However the wikipedia page is a simple generic formula.
But when investigating why my rank has decreased after a win just today (2020-05-03 dhpmrou win against jacob.harison09 who had a temporary rank, my rank dropped from 11.7k to 11.6k in 15’), I found scattered information in the forum, like the rank is computed from the last 15 matches (or one month if less), that the rank is recomputed from the current rank of past opponent (it seems). Plus there is an allusion at a change of calculation of the rank end 2018 (?), so it is not quite clear when reading a post whether this information is obsolete or not.
It would be very nice to have an uptodate, complete, technically accurate description on how the rank is actually computed.
Btw, I believe the most common reason a rank can decrease after a victory is simply because the opponent rank is worse than the one of the opponent of a victory 15 games in the past which is not taken into account any more. Well if the rank calculation technique I pieced together is the correct one.
Thank you for your attention.
David

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Yeah the way it works is “hidden” deep inside the forum… the first post here is about how glicko2 is implemented, the way how ratings convert into ranks is on post 29:

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Many thanks, it should really be made more prominent. I for one had not understood this 15 games thing, I thought this was a running 15 game batch.

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No problems, you’re not the first one who has looked for that info xD

I think glicko2 and the formula of how rating turns into ranks should be more visible on the main site, its maybe one of the most frequently asked questions here ^___^

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The exact explanation of glicko2 is 4 pages long, plus a 2 page example. All in beautiful math.

http://www.glicko.net/glicko/glicko2.pdf

I added both URLs to the documentation.

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