Yaku compatibility
This is a table showing the compatibilities of the different yaku with each other. While yaku may be combined in one hand, it is simply impossible to combine certain yaku with each other.
Overview
Yaku may not combine for two major reasons:
- Conflicting definitions. Tanyao requires the hand contains no honor tiles, but yakuhai requires a triplet of honor tiles, so the two cannot be combined.
- When a yaku always implies another yaku, they cannot score together. For instance, a junchan hand has a terminal in every group. Chanta requires that the hand has a terminal or honor in every group. Because every junchan hand would also qualify for chanta, chanta is not scored.
- There are two partial exceptions to this rule:
- Shousangen always implies two dragon yakuhai, but does not guarantee you have any one of "haku", "hatsu", or "chun".
- Ippatsu must be scored with a hand that declares riichi. However, "riichi" and "double riichi" are considered as 2 distinct yaku. Therefore, an ippatsu hand does not guarantee "riichi", since it could also be "double riichi".
When two yaku imply each other, as with reason #2, there are two alternate ways to define it in the rules:
- "Alter the yaku definitions so that they can never be scored together". In these rules, chanta is scored when there are honors/terminals in each group, and in addition, the hand must contain at least one honor tile.
- "Yaku that imply each other cannot be scored". In these rules, chanta is scored when there are honor/terminals in each group (not requiring an honor tile). However, chanta and junchan are never scored together. Junchan is worth more, so it supersedes chanta.
Both definitions are equivalent for any practical case. Most of these combinations, with the exception of toitoi + mentsumo, are based on the assumption that the yaku are defined using the second method.
Indirectly illegal
There are a few combinations that are indirectly impossible due to the implication rule.
Four combinations actually form yakuman:
- Toitoi + Junchan = Chinroutou
- Toitoi + Mentsumo = Suuankou
- Honroutou + Junchan = Chinroutou
- Double riichi + Chankan is only possible with a Kokushi musou hand
Some combinations form a different yaku which implies one component of the combination, and as a result can never be counted:
- Toitoi + Chanta = Toitoi + Honroutou
- Chiitoitsu + Chanta = Chiitoitsu + Honroutou
- Honitsu + Tanyao = Chinitsu + Tanyao
- Honitsu + Junchan = Chinitsu + Junchan
- Chinitsu + Chanta = Chinitsu + Junchan
These combinations are marked with 
in the table below.
Yaku
| Key | |
|---|---|
| Abbrevation | Yaku |
| RCH | Riichi |
| DRI | Double riichi |
| IPP | Ippatsu |
| SMO | Mentsumo |
| TAN | Tanyao |
| PFU | Pinfu |
| IPK | Iipeikou |
| ITT | Ittsu |
| YAK | Yakuhai |
| SDJ | Sanshoku doujun |
| SDO | Sanshoku doukou |
| TOI | Toitoi |
| SNA | Sanankou |
| SNK | Sankantsu |
| CHA | Chanta |
| JUN | Junchan |
| RPK | Ryanpeikou |
| SSG | Shousangen |
| HRO | Honroutou |
| HON | Honitsu |
| CHN | Chinitsu |
| CHI | Chiitoitsu |
| RIN | Rinshan |
| HAI | Haitei |
| HOU | Houtei |
| CHK | Chankan |
Nagashi mangan is excluded, because it is incompatible with anything, even riichi.
Compatibility
^ Ippatsu requires riichi to be of any use.
| RCH | DRI | IPP | SMO | TAN | PFU | IPK | ITT | YAK | SDJ | SDO | TOI | SNA | SNK | CHA | JUN | RPK | SSG | HRO | HON | CHN | CHI | RIN | HAI | HOU | CHK | |
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| DRI | |
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| IPP | |
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| SMO | |
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| TAN | |
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| PFU | |
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| ITT | |
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| SDO | |
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| TOI | |
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| SNA | |
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| SNK | |
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| CHA | |
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| SSG | |
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| HRO | |
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| HON | |
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Yakuman
Yakuman may not combine with regular yaku. However, in certain rulesets, different yakuman can combine with each other. As a result, hands can score multiple yakuman.
The maximum number of distinct yakuman a hand can have is four: suuankou, tsuuiisou, daisuushii, and one of tenhou/chiihou/suukantsu. In rulesets where suuankou tanki and daiisuushi are scored as double, the hand ends up with a sextuple (x6) yakuman.
Compatibility
| KMU | DSG | SUA | SSS | DSS | TSU | RYU | CHR | CHU | SUK | TEN | CHH | ||
| Kokushi musou | KMU | |
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| Daisangen | DSG | |
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| Suuankou | SUA | |
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| Shousuushii | SSS | |
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| Daisuushii | DSS | |
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| Tsuuiisou | TSU | |
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| Ryuuiisou | RYU | |
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| Chinroutou | CHR | |
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| Chuuren poutou | CHU | |
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| Suukantsu | SUK | |
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| Tenhou | TEN | |
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| Chiihou | CHH | |
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