Minkan

Minkan

Minkan (ミンカン) is an open kan, a set of four identical tiles formed by adding a tile to an existing pon (triplet) or by calling a fourth tile from another player’s discard. The term literally means “open kan” and is fundamental to understanding melds and hand development in mahjong.

Minkan in detail

A minkan occurs when you add a fourth tile to a pon you already possess, or when another player discards a tile that completes your set of four identical tiles. Unlike an ankan (closed kan), which is formed entirely from your concealed hand, a minkan exposes at least one tile and signals your hand composition to other players.

Formation Methods

There are two primary ways to form a minkan:

Adding to a Pon: If you have already called a pon (three identical tiles), you may add a fourth identical tile from your hand to create a minkan. This is sometimes called a “late kan” or “added kan.”

Calling from Discard: When another player discards a tile that matches three identical tiles in your hand, you may call minkan directly. This is also known as daiminkan (大ミンカン, “big open kan”), though the terms are often used interchangeably.

Dora Implications

One of the most significant aspects of minkan is its relationship to dora. When you form a minkan, you draw a replacement tile from the dead wall (a rinshan tile), potentially increasing your hand’s value. The tile following the kan indicator becomes a new dora, and if you later form an ankan, additional dora may be revealed. This mechanic makes kan a strategic consideration throughout the hand.

Hand Opening

Calling minkan immediately opens your hand. You can still win by tsumo or ron, but you lose closed-hand yaku such as riichi, menzen tsumo, and pinfu, so the hand must still contain at least one valid yaku. This is a critical trade-off: you gain dora and hand development, but you lose the ability to win independently.

Timing Considerations

The decision to call minkan involves careful judgment. Early in the hand, forming a minkan may help you complete your winning hand faster and reveal additional dora. However, it also signals your tile needs to other players, who may avoid discarding tiles that would help you. Late in the hand, forming a minkan might be too risky, as you become dependent on others’ discards to win.

Minkan at the table

You have three bamboo tiles (3-bamboo) in your hand and have already called a pon of 3-bamboo from a previous turn. Another player discards a 3-bamboo. You call minkan, exposing all four 3-bamboo tiles. You draw a replacement tile from the dead wall, and the dora indicator advances, potentially creating new dora tiles. Your hand is now open, so you will need an open-compatible yaku such as yakuhai or tanyao to win.

Alternatively, if you earlier called a pon of 5-character tiles and later draw the fourth 5-character on your regular turn, you may add it to that pon to form a shouminkan, drawing from the dead wall and advancing the dora indicator.