Tsumo - Riichi Mahjong Glossary

Tsumo (自摸)

Quick Definition

Tsumo is a winning condition in mahjong where a player completes their hand by drawing a tile from the wall themselves, rather than claiming a discard from another player. When winning by tsumo, all three opponents contribute to the payment.

Detailed Explanation

Tsumo, written as 自摸 in Chinese characters, literally means “self-draw” or “self-touch.” It represents one of the two primary ways to achieve a winning hand (agari) in mahjong, the other being ron.

How Tsumo Works

During normal play, each player draws a tile from the wall at the beginning of their turn. If the drawn tile completes a winning hand according to the rules and scoring conditions of the variant being played, the player declares tsumo and wins immediately. The hand must be complete with all melds properly formed and must satisfy the specific winning criteria of the game variant.

Payment Structure

The key distinction between tsumo and ron lies in how winnings are distributed. When a player wins by tsumo:

All three opponents pay equally to the winner
The payment amount is calculated based on the hand’s point value
In some variants, the player who drew the winning tile from the wall (the discarder in ron situations) may pay a slightly higher amount than the other two players
The total payment is typically lower per opponent than in a ron situation, where only the discarder pays

Strategic Significance

Tsumo wins are considered slightly less valuable than ron wins in terms of point distribution, which reflects the reduced pressure on other players. However, tsumo remains a crucial winning method and often represents the most efficient path to victory, as players need not wait for opponents to discard specific tiles.

Skilled players often build hands that can win by tsumo to maintain flexibility and increase their chances of completing their hand before opponents can block them through strategic discards.

Variations by Ruleset

The exact payment structure and point calculations for tsumo vary depending on the mahjong variant:

Riichi Mahjong: Uses standardized tsumo payments based on hand value
Cantonese Mahjong: May have different payment ratios
American Mahjong: Operates under distinct rules with its own scoring system
Japanese Mahjong: Features complex point calculations with payments distributed among all three opponents

Conditions and Restrictions

Not all hands can win by tsumo. Certain conditions must be met:

The hand must be fully formed (typically 14 tiles in standard play)
All melds must be properly declared or concealed according to rules
The hand must meet minimum point requirements (yaku in Japanese mahjong)
In some variants, special restrictions apply to winning on the first draw (haipai)

Usage Example

During a game of riichi mahjong, Player A has been building a hand and declares ready (riichi). On their next turn, they draw a tile from the wall that completes a sequence, forming a winning hand. Player A declares “Tsumo!” and reveals their complete hand. All three opponents—Players B, C, and D—each pay Player A an equal share based on the calculated point value of the winning hand.

Ron — Winning by claiming a tile discarded by another player; typically results in higher payment from the discarder alone

Agari — The general term for a winning hand in mahjong, encompassing both tsumo and ron victories

Menzenchin — A concealed hand where all melds are formed by self-draw rather than claimed from discards, often providing bonus points for tsumo wins

Haipai — The initial hand of 13 tiles dealt at the start of the game; winning on the first draw is called tsumo haipai in some variants

Draw — The action of taking a tile from the wall, which may result in tsumo if it completes a winning hand

Definition