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.

This page will assume you are declaring closed kan / added kan, unless otherwise stated.

Assessing kan

Advantages

• Reveals an extra kandora. Players in riichi also benefit from kan uradora.
• Gives an extra tile draw, with a chance for rinshan if in tenpai.
• Increases the hand's fu.

Disadvantages

• Opponents can benefit from kandora if they win.
• The kanned tiles cannot be discarded or used in the hand.
• Reveals the called tiles in your hand.
• An open kan will open your hand.

Kan during riichi

Main articles: Riichi and Kan#Restrictions

When playing with real tiles, players in riichi 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.

Kan when likely to win

Kan is an aggressive move. You only benefit from kan if you win. Conversely, if you win, your opponents cannot benefit from the kan dora. Therefore, you should prefer to call kan when you believe you have a high chance of winning. For example, kan when you are already in tenpai (and no one else is in tenpai), and kan with a good 1-shanten hand if early in the game (turn <8).

Players in riichi benefit from twice the dora (kandora + kan uradora), so a kan during riichi is especially helpful.

Conversely, if an opponent is in tenpai, you should not kan, unless desperate, or if you are also in tenpai. When you and an opponent are in tenpai, the decision to kan will depend mostly on point standing and your tenpai wait.

Situational analysis

Main article: Situational analysis

Kandora increases the score of everyone's hand. Therefore, the decision to kan can change depending on the point standings and current round.

• Players far ahead in the lead should not kan. The extra points benefit your opponents more than you: extending your lead doesn't help you much, but your opponents can certainly use the points to surpass you.
• Players that are behind when near the last round might be desperate to kan for the extra points.

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 added kan, 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 hope 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

Main article: Tile efficiency

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

Main article: 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.