Yaku

Yaku 「役」 are specific hand patterns or conditions that score points, analogous to poker hands. Each yaku is worth a specific amount of han, and multiple yaku can be combined into one hand. It is not expected of new players to know every yaku, but learning the most common yaku is important. Most importantly, every hand must include at least one yaku in order to count as a winning hand.

Han

Main article: Scoring

Each yaku is assigned a han value. Whenever a player wins, their hand's yaku are summed up, and the hand scores points based on the total amount of han. If a hand has multiple possible interpretations, the highest possible hand is scored.

Open vs closed

Main article: Menzenchin#Yaku

A hand is considered open if it makes a tile call from another player's discard. These include chii, pon, and open kan. Otherwise, it is closed.

Some yaku can only be scored closed; they are invalidated when the hand opens. Other yaku reduce in value if part of an open hand. The rest of the yaku score the same regardless if a hand is open or closed.

Nomi

Nomi 「ノミ」 refers to a hand that contains only one yaku and no dora. For example, riichi nomi 「リーチノミ」 means "riichi only". The term is mostly used for low value yaku, like tanyao and pinfu. It is acceptable to use it for higher value yaku, like chinitsu, but this is rarely done. The term is not used for yakuman, due to their value.

Yaku types

Yaku are scored based on hand composition and how the hand was won. Most yaku focus on what tiles the hand had; a few are based on where the winning tile was obtained.

Riichi

A player can choose to declare riichi with any closed hand that is tenpai (one tile away from winning).

Riichi

Any closed hand in tenpai may choose to declare riichi, scoring this yaku.

Double riichi

A riichi on your first turn is a double riichi, which is worth more points.

Ippatsu

After declaring riichi, if you win by your next tile draw, you score this yaku. (Invalidated if anyone makes a tile call.)

Win location based

These yaku are dependent on how you win the hand. These yaku can allow otherwise "yakuless" hands to win.

Discard based

Chankan

Winning with a tile used for an added kan by another player.

Houtei raoyui

Winning off of the last possible discarded tile for the hand.

Draw based

Haitei raoyue

Winning with the last tile draw.

Menzenchin tsumohou

Drawing the winning tile with a closed hand.

Rinshan kaihou

Drawing a winning tile after a kan call.

Honor based

These yaku depend on the use of honor tile groups. These may be mixed with number tiles.

Honitsu

All tiles are the same suit or honor tiles.

Honroutou

All tiles are honor or terminal tiles.

Shousangen

Two dragon triplets, and a pair of the third dragon.

Tanyao

No honors or terminals are used.

Yakuhai

A triplet of: your seat wind, the round wind, or any dragon.

Sequential

These yaku require sequential tile groups.

Iipeikou

Two identical sequences (two sequences with same suit and numbers).

Ittsu

A complete string of 1-9 tiles, arranged into sequences of: 123, 456, and 789.

Pinfu

Every tile group must be a sequence (among other conditions).

Ryanpeikou

"Two iipeikou"; two sets of identical sequences.

Sanshoku

Three identically numbered sequences, one of each suit.

Terminal based

These yaku revolve around terminal, or complete lack thereof.

Chanta

Every tile group, including the pair, has an honor or terminal.

Honroutou

Every tile is an honor or terminal.

Junchan

Every tile group, including the pair, has an honor or terminal.

Nagashi mangan

Every discarded tile is either a terminal or honor

Tanyao

No terminals or honors are used.

Triplet based

These yaku require at least one triplet in order to be valid. Quads count as triplets for these yaku, but triplets don't count as quads.

Sanankou

Three closed triplets.

Sankantsu

Three quads.

Sanshoku doukou

Three identically numbered triplets across the three suits.

Shousangen

Two dragon triplets, and a pair of the third dragon.

Toitoi

Every tile group is a triplet.

Yakuhai

A triplet of: your seat wind, the round wind, or any dragon.

Suit based

Honitsu

All tiles are the same suit or honor tiles.

Chinitsu

All tiles are the same suit.

Yakuman

Main article: Yakuman

Yakuman is a special class of yaku. Yakuman are worth the maximum amount of points, and cannot be combined with non-yakuman yaku. Theh are among the most difficult to complete, so players may treat them as special.

Combining yaku

Main article: Yaku compatibility

Yaku may be combined with other yaku. When a hand qualifies for two or more yaku, their han value is added up. Combining yaku and/or dora is important for scoring big hands.

Optional yaku

Main article: Optional yaku

Optional yaku, or local yaku, are yaku not included in the standard ruleset of riichi mahjong. These yaku may be added with house rules, increasing the game's complexity and number of available hands.