Riichi mahjong statistics have surfaced all around the Japanese internet, making their way into the western circles as well.

However, how important are they actually? Should you take the time to memorize all the edge cases?

If you’ve ever wondered about the importance of statistics in mahjong, you’re not alone. After all, Japanese mahjong is a game where you can play the odds and still sometimes lose. However, I’d like to clear up some misconceptions about data and how some professional mahjong players, myself included, think about the game.

Do Mahjong players use “feeling” or “statistics and data”?

Ah, the old debate. Occult or digital, John or Paul, religion or science, chicken or egg. Maybe not that last one.

Do Japanese mahjong players constantly use data to calculate and decide what the best move is?

The answer is: Yes... but no… partially!

You might be surprised to read many of the strongest players right now lean towards a more “humanistic” approach, taking into account a lot more meta-information, adopting bluffs and other strategies in the heat of the moment, much like Poker players have been doing.

Statistics and data pave the path for having a stable, “standard” choice when everything else is equal.

Orthodox digital players might tell you that the right way of playing mahjong is simulating or calculating the Expected Value of every single discard to decide what the correct choice is and that the result of such analysis will always yield "the one correct discard". That is not what real "digital" play is all about.

EV (in a vacuum) is a vital factor for deciding discards, but it’s not the only one. Years of experience will eventually teach you about factors that can’t (yet) be accurately measured.

Mahjong Statistics and Hand Reading

Say for example, do you know the probability for hon itsu tenpai for somebody with 2 calls of the same suit during the second row of discards? Someone already has data for this, tho a lot of people don't know it by heart. But, there's a catch now, there are many other factors to consider.

How about if he changed his hand 4 times after his last call?

Instead, how about if he discarded a dora ryanmen shape early on?

What if he did both of the above?

Wait: How about if he’s not the type of player who usually calls twice for less than 3900 points?

What if he’s right-handed and discarding everything from the right end of his hand? (The likelihood of hon itsu increases!)

Finally, what if he loses his rhythm or drops the pace before each yakuhai he discards? What if he doesn’t? What if he stutters whenever the person to his left drops a tile in that suit?

Let’s not even get started with what tiles he called, didn’t call, or what his discard area looks like.

The point is: there’s a lot of meta-information on the table and although statistics and data can help, they cannot yet take an exact measure that takes all this data overload into account.

The data available would not be enough to cover every specific case, and even if it were, it would be next to impossible to memorize every single case and combination.

(If you’d like to see some more examples of how to read Hon Itsu hands effectively, you can subscribe to my Patreon and get access to special posts like this.)

Statistics are made different: the source of the data matters!

Most data nowadays comes from Houou (Phoenix) tables on Tenhou.net which is a completely different ruleset (and player base) from your average mahjong tournament.

Phoenix Players represent less than 1% of the mahjong playing community. Usually, the people you encounter in real life will not be that good, and surely they will not play in the same way if the rules are different.

For example, you might encounter sakigiri and betaori more often in Tenhou than in High Rate Tonpuusen parlors.

Please, pick your statistics carefully; ideally use data from the ruleset that you're playing.

Mahjong has a lot of “gray” areas when it comes to decisions. Strong players are just good at telling apart the whiter shades of gray from the darker ones


How much should I rely on mahjong statistics?

When you have no other relevant information, data and statistics should always come first. So, yes, you should learn at least some basic statistics like how likely are you to draw a ryanmen, or how often is ippatsu tsumo expected (this will also help you manage frustration).

However, as you become stronger and you start to pick up more and more reliable info, you can start twisting those numbers around. Shape the Matrix and dodge bullets! (or maybe you won't have to)

Deviating from statistics is not a mistake, it is a privilege.

You’d be surprised at how the legendary mahjong players manage to turn the tides in their favor and beat the odds thanks to their experience. Legendary Meijin Tsuchida Kosho is one such example.

Learn the rules like a pro so you can break them like an artist!


You can get more valuable practice with these riichi mahjong tools and resources.

If you'd like to tap into my own expertise, schedule a mahjong lesson with me and I'll be happy to help you achieve your goals.

Good luck at the tables! Please share and like this post if you found it useful, and see you next time!