Alignment of OGS & kgs/AGA ranks

This is intended as sort of an open letter to the devs:

I know you guys have put a great deal of thought and effort into improving the rank system here with great results. Thank you! It seems from my personal experience that there is still a pretty big discrepancy between OGS and KGS/AGA in the high SDK/low DDK range, and it has caused one minor real-world problem for me. I just started participating in my first small AGA tournaments, and a couple people showed up for their first tournament and gave the TD their OGS ranks. This caused some games with really inappropriate handicaps because it seems that the OGS ranks are pretty deflated from AGA in the 10k range. It wouldn’t be an issue if everyone was aware of the deflation and acknowledged it, but I’ve noticed an attitude among some players that OGS has the “real ranks” and every other site’s ranks are inflated. I’m just not convinced that this is accurate.

I found this recent entry on Sensei’s Library ( ):

tapir: The internal conversion of KGS ranks is: R(OGS)=2dan + 1,5 * (R(KGS)-2dan). Gnugo being rated around 14k on OGS against around 8k on KGS is pretty much in line with this. Also other data supports this conversion.

This seems pretty accurate for me (7-8k on kgs / 11-14k OGS).

It’s also caused some confusion regarding getting level-appropriate advice on r/baduk. If a more established player is used to giving advice based on KGS rank, then advice they give to me as an OGS 12kyu is not going to be appropriate if I am actually what they would consider a 7kyu. I’ve got it somewhat figured out now, but it wasn’t clear to me at first what was going on.

Is there any thought being given to performing an additional rank realignment?


No ranks are “real ranks,” every ranking system is totally subjective. That is why we say (or at least we should) “i’m 12k OGS” or “i’m 7k AGA” and so on.

That being said, i think we should have another mass adjustment soon, it’s not as bad situation like it was last summer, but still.


The four different ranking systems don’t seem to make sense either. I’ve noticed that with a few players (myself included) that the overall rank is a whole rank difference from the other three ranks where as it is supposed to be a combination of the three.

I do agree with Koba though. All ranking systems are subjective. Any real world tournament should take that into account.

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I will confirm that there is a rank discrepancy around that level, at least from my experience. I finally got a computer that could handle java, and joined KGS, I estimated my strength to be between 7-10k, assuming that if discrepancy did exist, it would probably be OGS that was the weaker of the two sites. (my logic being that larger player base = tougher ranking)

Contrary to my expectations, I played two games, one against an 8k and one against a 9k. I beat both so badly it felt a four stone handicap would have been needed to even out the games.

As to whether that means our ranking needs an overhaul… well I’ve only been here a year, and played 200 games or so, but from what I see there’s no need for it. As has been better stated by those above.

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I’m sorry about my ignorance on the subject, but…even if devs make a massive adjustment of rankings, wouldn’t a discrepancy re-appear after a few months?

That allways puzzled me too when people talked about the ranks on OGS being stronger that the ones on KGS

There are a variety of reasons it could be, I’m sure. I’m not savvy enough about the math that goes behind ranking systems to know most of them, though.

From a player perspective… one reason I can think of for the discrepancy is that there are a LOT of players on KGS who abuse the blitz time system to grossly inflate their rank. I know they were having issues a few years back with people doing that until they were mid-dan, then bilking new players for paid lessons.

that wouldn’t explain why the discrepancies happen more at the SDK/DDK range, though…but a lot of those are pretty subjective.

It would be very hard to bring all of this into alignment since players really dislike being demoted. In a sane world, all amateur ranks would have a relationship with pro ranks as is the case in Europe, but that is not this world. Way back when I assumed that online play would tend to bring the ranking systems together, but if anything the opposite has happened.

Anyway,. I’m new here and wanted to make sure I was playing at the correct rank. The Sensei’s table says 1d here is 1d at KGS, but is that correct? Not being a programmer, I wasn’t sure how to use tapir’s formula. TIA.

TBC, the table to which I refer is at

I’ve seen that sensei link before. As it was said previouslly on the post, there’s a big discrepancy in SDKs and strong DDKs rank. I don’t know about dan-level players, but I suppose a KGS 1dan is probably 2k or 3k here. You’ve already set your rank, so it’s late to change it on your own now.

Thanks. No biggie, I’ll just lose a few games until I get settled.

It seems nobody has a really idea how the ranks are compared.
There is one guy on sensei’s with this formula, and that’s all we got :smile:

As a first step, it is better to gain more insights in the shifts and trends.
If we have a better understanding of the ranks here at OGS, compared to KGS/AGA/EFG, this can help the devs to make adjustments, and can help you to give a more accurate estimate of you KGS/AGA/EFG rank for tournaments.

I don’t think such insights are that difficult to make, with a few (30+) KGS reference players, and a few (30+)AGA/(30+)EGF reference players, i am sure even I can make some pictures showing what is really going on.
This insight can be calculated each week, to see trends.
Of course, we need a bunch of reference players willing to tell their KGS/AGA/EGF account, for the calculations to work.

If people think this is useful and willing to help, let me know. Could be something worth to put some effort in before.


That one guy on sensei’s is me, in case anyone is wondering.


Real ranking system should not count 9x9/13x13 boards.


Aaah, so you are that guy on sensei’s!

I was summoned … please be aware that the rank tables, rank discussions on Sensei’s are very dated. My quoted entry was from June 2009 ( and refers to a correspondence only OGS before merge and changes to the rating system.
The obvious solution to OP’s problem would be to always ask on which server the rank was achieved. Though my intuition is that OGS has still too few handicap games and thus ranks are closer to each other than they should.

So OGS ranks are close to EGF ranks and KGS ranks are close to AGA ranks.

And now people from the US are pushing for an alignment with AGA ranks while at the same time accusing OGS players of wrongly thinking that they have “real” ranks.

Why am I not impressed with this US-centrism?

If you want to switch the ogs ranks to your country’s ranks that’s understandable, but try to do so without showing that you never thought about the existence of other countries or the possibility that their ranks might be “real”.

What thread are you reading? If you want to be political, please do it somewhere else.


Maybe what he meant is that we should be looking to an alignment of some kind with KGS (which is a site that covers worlwide) instead of be thinking about what OGS people’s rank should they use on AGA. Although OP was talking about his personal situation on the US, so it’s no wonder people are talking about AGA.

I am reading a thread where someone puts “real ranks” in scare quotes because they do not correspond to US ranks.

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We call that scaremongering. Please do not engage in such hysteria. This particular person is (wrongly) concerned that different ranking systems are not matching up. They use AGA as an example because that’s the system with which they interacted.