Kan strategy
Kan is a naturally risky action, due to the nature of kandora. When a player calls kan, any player - including the kan-declarer's opponents - may benefit from the kandora. Therefore, some assessment should be made when calling kan.
Offense
Kan is usually an offensive move. The player gets an extra draw from the rinshanpai and chances for the kandora. If the hand is tenpai, then the hand has a chance for rinshan kaihou.
Most importantly, if the kan-declaring player wins, then their opponents will not benefit from the kan dora. Therefore, if the player believes that they are likely to win the hand (e.g. reaching tenpai early, or iishanten very early), then kan is stronger than usual.
Riichi
Players in riichi benefit from twice the dora: a kan dora and a kan ura dora. Also, a player in riichi is already in tenpai, so they are more likely to win. In addition, the threat of kan dora will make your riichi more threatening, encouraging players to fold (folding players do not benefit from kan dora). Therefore, kan during riichi is particularly strong, assuming it is possible.
If you are in riichi, but someone appears to be pushing against you, it becomes a more risky play. If you happen to be far ahead in the lead in this situation, consider not calling kan.
When playing with real tiles, players must always be aware of whether a kan call can legally be called. Players using game software or online platforms do not need to be aware because the programs handle the situations for them.
Defense
A player in betaori (full folding) should usually avoid declaring kan, because it removes four discard options from your hand, and may increase the opponent's score. For shouminkan/kakan, there is an added risk of chankan.
Any player can apply kabe when somebody calls kan. If all four tiles are visible, e.g. from an opponent's kan call, then it will make certain types of wait impossible. For example, If a kan of 3 is called, then the wait patterns of 23, 34, and 13 of the same suit are impossible. Thus, 1 and 4 become safer. If all four tiles are in your own hand, then there's no need to actually call kan in order to benefit from kabe.
If you have no safe tiles, a possible play is to call kan and hopes to draw a safe tile. However, since you'll likely increase the score of the opponent, this is a somewhat dubious play. In addition, the kan tile could become safe later (e.g. becoming suji), and then you will lose four tiles. Therefore, you should try avoiding this unless it's late into the hand.
Shifting the draw
When a kan is called, one tile from the live wall shifts over to the dead wall. Therefore, kan can be used to deny ippatsu and/or the haitei draw.
Delaying kan
Kan is not mandatory, so players do not have to call kan immediately. Instead, they can keep the fourth tile in their hand, declaring kan if/when appropriate. This gives more flexibility - e.g., if you draw the 4th copy of a tile, then an opponent declares riichi on the next turn, you will be glad that you did not kan. However, delaying the kan will often reduce tile efficiency (if you are not using the tile for the hand).
Under most circumstances, you should not call kan if it would break up a sequence. For example, if you have a 555567 in your hand, it can be considered as two groups: 555 + 567. Calling kan would ruin the 567 sequence, thus slowing down your hand. But if you then draw the 8, then the sequence is retained, so kan no longer slows the hand.
Fu
If you are at 3 han or lower, the extra fu from kan can increase the hand score.
| English | Romaji | Simples | Honor/Terminal |
|---|---|---|---|
| Open kan Added kan |
Daiminkan Shouminkan |
8 fu | 16 fu |
| Closed kan | Ankan | 16 fu | 32 fu |
A closed kan with an honor/terminal tile gives 32 fu, which is not far off from gaining +1 han. As the most extreme example, a 3 han 40 fu ron would give 5200 points; declaring a closed kan with an honor/terminal upgrades it to 3 han 70 fu, a mangan (8000 points). In other cases, the fu is only a small boost to score, so should only be accounted for in tight point situations.
External links
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