MahJong Rules

MahJong Rules

Copyright © 1996 Thomas Zuwei Feng

This document describes MahJong rules and their incarnation on the Internet MahJong Server (IMS).

MahJong Tiles

There are a total of 144 tiles in MahJong, they can be classified into the following categories:

The Character Suit

The Ball Suit

The Bamboo (or Stick) Suit

From left to right, the tiles have values 1 to 9. There are 4 tiles for each value.

The Winds and Dragons (collectively called Words)

The first 4 are wind tiles that correspond to the 4 directions: East, South, West, and North. There are 4 for each of these tiles. This is also the order players' seats are named on the MahJong table: starting from the dealer being East, rotating counterclockwise up to North.

The last 3 are dragon tiles, again there are 4 of each.

The Flowers

All the flower tiles are distinct. They are not normal tiles and play relatively minor roles in MahJong, mostly to introduce the factor of "luck". Some versions don't even use them, but we do.

Sets of Tiles

Here are some terminologies for certain sets of MahJong tiles. Various people have various different names for them so beware. A [normal] winning pattern consists of 5 sets of normal tiles. One of the sets must be a pair, the other 4 sets can be connections, triplets, or quadruplets. You can also have any number (including 0) of flower tiles. Here is an example:

Games and Rounds

There are 4 players on the table. A random player is chosen to be the dealer. Each player then gets assigned a seat wind, starting from the dealer being East, proceeding counterclockwise in the order of the wind tiles. There is also a round wind for each game, for the very first game it's always East.

If the dealer wins the game or if the game is a draw, then he remains the dealer for the next game. However, if someone other than the dealer wins the game, then the next player in turn (who used to be South) will be the dealer for the next game.

When the dealer has rotated a full round back to the very first one, the round wind rotates to the next one in the wind tiles.

A MahJong Game

In a MahJong game, each player conceals his private hand of tiles and reveals some of them as the game progresses. Once some tiles are revealed, the player can no longer touch them. There is also a big stockpile of concealed tiles to be drawn from.

To draw a tile, a player takes a tile from the stockpile on the table. If it is a flower, he reveals it and keeps drawing until he gets a normal tile. NB: in normal games, players draw tiles from the beginning or the end of the stockpile depending on the situation. We don't make that distinction in IMS.

Initially, each player draws 13 tiles. The dealer draws a 14th one, and the game starts, the dealer having the turn.

The player in turn has the following options:

If the player doesn't win, eventually he has to discard a tile. Then the other 3 players make bids for that tile and the next turn to play.

For the immediate successor (in counterclockwise order) of the player who just made the discard, he has the following choices:

For the other 2 players, they have the following choices: Note that only the immediate successor can make connections.

Bids have the following order of precedence:
pass < draw & connection < triplet & quadruplet < MahJong.

If the table allows multiple wins, then all players who claims MahJong win the game. Otherwise, only the closest successor (in counterclockwise order) of the player who just made the discard wins. The player who just made the discard is the feeder.

If nobody wins, the player who has the highest bid makes his play:

Then, this player gets the next turn.

After someone wins the game, or if the game is a draw, the dealer, round wind and seat winds are rearranged (see Games and Rounds) and a new game starts.

IMS Table Options

There are certain options that you can set in IMS to have minor changes on the game and scoring. They are there mainly because there are literally dozens of different MahJong conventions, and we try to accomodate them within the general framework set of IMS.

IMS Scoring System

For each winning hand, we calculate two variables: fan and bonus. Fan is calculated additively from the following rules, up to a maximum of 13.

We refer the reader to MahJong Tiles and Sets of Tiles for some terminologies used below.

Plus the following special patterns: The bonus is calculated as follows: The score of a hand is calculated by: Payment in terms of points is made by:
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