Tenpai

Tenpai is also referred to as the "ready hand". A hand is tenpai or "ready" when only one more tile is needed to complete the hand. The completion may be either done by draw and/or discard, where applicable. Tenpai does not require that the completed hand has a yaku, although both a completed hand and a yaku are necessary to win.

Being one or more tiles away from tenpai is called noten. This word is a contraction of the English no tenpai.

Having achieving tenpai is worth some points when a hand ends in ryuukyoku.

Example tenpai hands

Closed tenpai

Open tenpai

Exceptions

Karaten

Karaten, or empty tenpai, is an exception to the rules given so far. Specific rules may consider an apparent tenpai hand to be noten under the following circumstances.

All hand-completing tiles are already used within the player's own hand. Declared kans and open melds belong to the hand. If a player has a 1-2 penchan and a previously declared kan of 3-3-3-3 in the same suit, no more threes are available as winning tiles. Under most rules, this is noten.

All hand-completing tiles are visible among declared kans, open melds, discards, and dora indicators. Only some rules have such a large scope for karaten.

Dead hand

A player with a dead hand is never considered tenpai.

Tenpai with no yaku

The definition of tenpai does not refer to yaku.

This is a common pitfall for many beginners. Hands are achieved by tenpai. However, due to lack of or limited knowledge of the yaku, players may find themselves building a hand to tenpai but are unable to declare a win. Furiten may be a case here; but often, this is due to the lack of yaku.

In this state, it is still possible to produce yaku via haitei, houtei, and even possibly rinshan. This is particularly true of open hands. For closed hands, tsumo may count as an additional option.