The Art of Winning in Riichi Mahjong: Understanding and Calculating the Chances

Nicolas ProBy Nicolas Pro11 min read

Revealing the Art of Winning in Riichi Mahjong: Understanding and Calculating the Chances

How do you win in mahjong? What is the best strategy to take when playing this game? These are two of the most common questions asked by people who have never played mahjong before.

The answer, however, is not so simple. While it's true that there are a number of strategies that can be used to increase one's chance of winning, understanding the ruleset and calculating the chances for yourself is much more important.

There is a theory that says strategy doesn't matter in mahjong. It's all about luck, and the only way to win is by getting lucky. This couldn't be further from the truth! In this blog post I will show you how to find your winning condition, I will discuss how to calculate your chances of winning when playing riichi mahjong and how to improve them.

Riichi mahjong is a game of chance. With the right timing and an understanding of probability, you can be winning one round as you get your opponent to discard useless tiles endlessly; and then lose five rounds in a row because it seems like luck has left the building. What type do you play? Winning riichi or losing riichi?

What does it mean to Win in Riichi Mahjong?

If you're reading this blog, I assume that you want to start playing your best winning mahjong. I also assume that you've been playing riichi for long enough to know that you cannot (and will not) win 100% of the time.

At the same time, no matter how bad you are you won't lose 100% of the time either.

Skilled pro players only take 1st place about 30% of their games, which in turn means they're "losing" 70% of the time.

In fact, most strong players unavoidably end in 4th place around 20% of the time. That's once every five games.

Strong players win 30% of the time, but they still lose 20% of the time ~NPMahjong

How bad do you want to win? No one is perfect and the game of mahjong isn't easy. Even if you're a skilled player, there's no guarantee that every time will be your turn for victory! You may have won 30% of all games in which you played up until this point, but how often are those wins happening consecutively? 20%-30%. That means out of an average five-game session with friends at home or online (of course!), four times it might not be your turn on stage.

Tenhou Players Stats

Although his opponents were very strong, keep in mind even Asapin only won 27% of his games when he first climbed to the top of the Tenhou.net ranks

Just because you're not a pro player doesn't mean that the game is rigged against you. The truth of it all, in fact, is just the opposite: most good players end up losing more often than they win!

Don't let your ego stop you from playing mahjong -- winning or losing (even if only occasionally) will teach something new about yourself and how to play better next time around.

RISK vs REWARD: The difference between a Winning Mahjong and a Losing Mahjong

Suppose for a second that you have access to three choices that will always get you the following results every game with the following probability:

Option A

  • 1st place 30% of the time
  • 2nd place 20% of the time
  • 3rd place 20% of the time
  • 4th place 30% of the time

Option B

  • 1st place 20% of the time
  • 2nd place 40% of the time
  • 3rd place 20% of the time
  • 4th place 20% of the time

Option C

  • 1st place 35% of the time
  • 2nd place 0% of the time
  • 3rd place 0% of the time
  • 4th place 65% of the time

These doors line up before you. You knock at one... which one is it? What choice do you make? Let me give you a minute to consider your answer.

Three doors lined up in a row

Behind two of these doors awaits a llama...


If you answered A, that's wrong. I'm sorry...

If you answered B, I have to tell you... wrong as well.

However, if you answered C… that one's wrong, too!

So... all answers are wrong?... what gives?

The only one right answer to this problem is:

WHAT ARE THE RULES? "What is my win condition?"

Depending on your winning condition, i.e. on the rules you’re playing, each of the above options can become the ideal choice.

Depending on what ruleset you are playing, the right choice will vary in Japanese mahjong

Yes, I'm sorry, this was a trick question. But an important one nonetheless!

Examples of Different Mahjong Rules

For instance, at the final table of a tournament where 1st place wins 200 points (or dollars, if you fancy) and the coveted title + bragging rights, and then 2nd, 3rd and 4th place all get 30 point$ each, then surprisingly Option C becomes the best choice.

I saw myself in this exact situation during the Shinjinousen Finals.

Especially in once-in-a-lifetime events, since you only get to play so few final tables in your life, it’s especially important that you choose the option with the highest probability for 1st place, regardless of all the other placements. 30%-70% coinflips are still a good gamble to take.

Depending on your winning condition, the ideal choice will be different! ~NPMahjong

However, if you chose Option C all the time in NPM League Games, where you play 80 games a year, and the point distribution is +50 +10 -10 -30, you wouldn’t be very successful in the long term. Unless, of course, it was the final game of the season and you needed a 1st place to win it!

Under NPM League rules, Option A would be optimal and preferred even over option B, because the bonus for 1st is much bigger compared to the penalty for 4th.

It's all in the rules.

Let's run a little thought experiment using the NPM League rules as an example.

Winnings Simulation

NPM League Point Distribution: 1

(25k in 30k out)

  • 1st: +50
  • 2nd: +10
  • 3rd: -10
  • 4th: -30

Suppose 100 games are played:

  • A: 50x30 + 10x20 – 10x20 – 30x30 = +600
  • B: 50x20 + 10x40 – 10x20 – 30x20 = +600
  • C: 50x35 – 30x65 = -200

That would be the EV (expected value) for each playstyle, as detailed above.

“Wait! A and B are both +600! You said choice A would be better than choice B. So what gives? Aren’t they just equally good? They have the same EV so they must be just as good!”

Yes, of course... if you played an infinite number of games. For league games, however, professional players only play 80 games a year. And even fewer for the lower leagues.

Since just the people on the top of the ladder move on, you want to prioritize the chance for first place, all other things being equal.

Once the scoreboard situation dictates that "you now need to hold at least 200 points to move to the next table" there will be no difference between holding 199 points and having 0 points, so you should prioritize the chance to move up in rank. If your lead on the scoreboard has grown large enough that it's a risk-free decision, then switching over to B and avoiding 4th place can be an excellent choice as well.

However, keep in mind that quite a few tournaments don’t add that huge bonus to 1st place, and might adopt a +20 +10 -10 -20 point spread alone instead. In those cases, choice B suddenly becomes the strongest option.


  • A: 20x30 + 10x20 – 10x20 – 20x30 = 0
  • B: 20x20 + 10x40 – 10x20 – 20x20 = +200
  • C: 20x35 – 20x65 = -600

I do realize that this is all very theoretical, and very rarely will you be consciously aware of whether you are taking a type A, B or C decision so accurately. Nevertheless, I just want you to see the principle behind it - **the same playstyle will yield very different results in different settings.**

Other Mahjong Winning Conditions (e.g. Online)

How about Tenhou (the internet mahjong server) for example? Or MahjongSoul?

Your best decision might change according to the point spread of the game you play.

It is up to you as a player to find what the optimal strategy is, and adjust your play accordingly.

Mahjong parlors, championships, etc., are all different. You have to find your winning condition and play for it.

1-day tournaments, where you only play 5-6 games at most, are perfect for those who want to go all in. Whether you win or lose, it doesn't matter as long as you get what you need from the tournament with each game played. The key is persistence! 5th place and 48th place likely all hold the same value. And you can just keep signing up to one-day tournaments over and over again over the year! There is no shame in getting last place at the end either. It's not about how many times or how hard you fail, but about how many times you succeed.

It does not matter how many times you get knocked down, but how many times you get up. ~Vince Lombardi

For example, Tenhou championships are made in a way that you need to win 5 games in a row to have a shot at winning the entire thing, and you can play any amount of games while the championship is going on. That’s the perfect time to use something like strategy C and increase your chance to score 5 wins in a row!

Winning in Mahjong Parlors

It's easier to tell whether you are a winning or losing player at a gambling mahjong parlor, because it will translate into something tangible: your wallet. It is a bit more difficult for no-gambling parlors, but usually they will have some sort of rating and ranking system.

Bear in mind that in Japan, officially and legally, "there is no such a thing as gambling parlors", and no professional players will admit to being linked to them. But, that is subject for a different blog post.

In mahjong parlors, you can either be more conservative or more aggressive, depending on the rules.

One extreme and odd example, the ruleset in Killer Tune (Umeda) (where I used to work at) would give 2nd place enormous value.

(Allow me to use the fictitious currency of "G" as "playmoney", for plausable deniability, because this is a public blog.)

Real Life Example:

  • 1st: +70G
  • 2nd: +30G
  • 3rd: -40G
  • 4th: -80G

(Sum them up and there is a 20G difference - that 20G difference goes to the house per each game played; a game usually lasts between 15 and 20 mins)

As you can see, falling from 1st to 2nd is only -40G, while dropping from 2nd to 3rd is a whopping -70G (almost double).

At the same time, climbing from 3rd to 2nd is a good +70G while falling to last is only -40G.

More importantly, you get an extra 10G from each player for each Red dora or bonuses in your hand when you win a round, so completing a hand is even more important than brooding over whether you're stuck in 2nd or 3rd.

This means players are less inclined to chase 1st place if it will risk them falling down to 3rd, yet a lot more likely to fight for 2nd place.

I didn't get too many 1st places during my time working there, but I still kept a very good salary and I like to consider myself a winning player.

If you think winning at mahjong is about "getting a lot of 1st places", you need to reconsider. Think again!

Winning isn't about just getting a lot of 1st places

To win in mahjong...

You cannot and will not win every game. So you have to understand what your win condition is and play according to it: in other words, adapt. Don’t play the same way under every setting, and don't follow statistics without context.

Don’t be afraid to end up 48th in a 48 people tournament only to prioritize a play style that will only make it more likely to end 10th each time (unless, of course, the rewards for 10th place are well worth it!). Feel free to play for the top, even if you might end up falling to the bottom - and don't fall victim to Tenhou Syndrome.

Mahjong isn’t a game of discards, it’s a game of rules.

The optimal play will vary greatly depending on what you’re chasing after. So find your win condition, measure risk vs. reward, and make your choices accordingly. “Winning mahjong” is all about making the right choice under the proper rules.

Playing a “Winning Mahjong” is all about making the right choice under the proper rules. Mahjong isn’t a game of discards, it’s a game of rules.

P.S.: If you would like to discuss your strategy before entering a tournament, drop me a line and let's schedule a web meeting together to get you prepared!

Good luck, and choose your strategy wisely from now on!

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