Shanten

Shanten is a term used in Japanese mahjong to describe the number of tile draws a player needs before a hand becomes a winning hand (called “reach” or “tenpai” in the next draw). The concept helps players gauge how close they are to victory and decide strategy during play. A hand that is already in a winning state has a shanten value of minus one, while a completed hand is sometimes said to have a shanten of minus one or zero depending on context. A shanten of zero indicates the hand is one tile away from winning. A higher positive value means more tiles are required.

The calculation for standard mahjong involves counting the number of sets (three tiles of the same rank or a run of three consecutive numbers in the same suit) and pairs needed to complete a hand. The common formula is: Shanten = 8 – 2 × (completed sets) – (pair present) – (koutsu or shuntsu in progress). Adjustments are made for hands with seven pairs or thirteen orphans. In tournament play, players often estimate shanten to evaluate whether to build a specific waiting pattern or to switch strategy.

Shanten is also used in score prediction. By knowing the shanten count, a player can assess the expected number of future draws required. This is useful for risk management and for determining whether to go for a quick win or to play more conservatively. The concept also applies to other tile‑based games; however, the term is most widely recognized in mahjong traditions across East Asia.