Japanese mahjong scoring rules

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Scoring Table.png

Japanese mahjong features a very complex scoring system. Every mahjong hand has a value in terms of han and fu associated with them. From a scoring table, the combination of han and fu then corresponds to values indicated. These values are derived using han and fu into the points equation, along with the appropriate multipliers.

By default, most games start players at 25,000 points, with the goal of scoring at least 30,000 to declare victory for the points leader. Point settings may be flexible to vary both the starting score and the goal score.

Scoring factors

For every winning hand, two scoring factors are used to determine point values: Han and Fu.

Han

Han 「飜」 is the main portion of scoring, as each yaku is assigned a han number. Most of the yaku are valued at either 1-han or 2-han. At most, a sole yaku can be worth 6-han. Anything greater may be classed as yakuman. Naturally, different yaku can be combined to produce hands worth 2-han to greater than 13-han.

In addition to knowing the yaku, players are encouraged to know their han values. This gives them greater awareness on potential point values of the hand. This knowledge may help aiding in various game decisions, particularly when calling riichi or abandoning the hand.

Some may factor being open or closed; for others, this would not matter. Any dora in the winning hand provides one extra han each. In general, an increase of value by one han roughly doubles the number of points, until the cap of mangan.

For most applications, yakuman do not have a han value. For the rarely used aotenjou rules, they are defaulted at 13-han. If a winning hand satisfies at least one yakuman, han and fu are not necessarily counted for the hand. Points are awarded based on the yakuman value. If multiple yakuman are allowed, then the yakuman values are multipled by the number of yakuman patterns in the hand. Finally, any hand that accumulates 13 or more han is counted for a kazoe yakuman.

Fu

Fu 「符」 (pronounced as foo) takes the hand composition into consideration in terms of tile melds, wait patterns and/or win method. Every hand begins with a default start value of 20 fu. To determine the final number of fu, the sources of fu are added up along with the base number and then rounded up to the next multiple of 10. The exception is the chiitoitsu yaku, which is fixed to 25 fu and is not rounded. While fu may be counted for hands worth 5 han or greater, it is not necessary. At 5 han and above, the hand value is dependent only on the han count, and the fu count is ignored. When playing with the uncommon aotenjou rule, however, the fu count is used for hands of any han value.

Scoring procedure

Calculating basic points

To determine the point value of a hand, the following procedure is used:

  1. If the hand is a yakuman, then hand scores 8,000 basic points × number of yakuman.
  2. Otherwise, determine the hand's valid yaku.
  3. Count the han based on the yaku.
  4. Count any number of dora to the han count.
  5. If the han count is 5 or more, then counting fu is no longer necessary. Score the hand according to its han value on the scoring table.
  6. If the han count is 4 or less, then count fu.
  7. After determining the number of han and/or fu, refer to the scoring table.

For any who prefer to use the equation, basic points for 5 han or less are computed as:

Basic points = fu × 2(2 + han); limit of basic points = 2,000, for mangan and beyond.

Payment multipliers

After determining the basic points, multiply based on the status as dealer and no-dealer as well as the win by ron or tsumo.

  • When a non-dealer wins by tsumo, the player earns 1 × basic points from the other non-dealers. The dealer in this case pays 2 × basic points.
  • When a non-dealer wins by ron, the discarding player pays the winner 4 × basic points.
  • When the dealer goes out by tsumo, the dealer scores 2 × basic points from all players.
  • When the dealer goes out by ron, the dealer earns 6 × basic points from the responsible non-dealer.

Finally with the multipliers applied, a hand's point value is finally expressed as:

Points = Basic points x Payment multiplier; points rounded up to the next 100.

Scoring table

The points derived from the equation and the payment multipliers are arranged in a scoring table. Players have the option of knowing the point scores by either deriving from the equation or brute force memorization.

Honba

Honba is an added counter to the number of consecutive hands, that did not produce a winning hand and/or the dealer position repeats. For each honba count, every hand is worth a total of 300 extra points. Once a winning hand does occur, the honba count resets back down to zero. The event of chombo may or may not produce a increase in the honba count; the common practice does not.

Summary

  1. Determine Han
  2. Determine Fu
  3. Refer to the scoring table, or memorize the corresponding point values
  4. Factor in honba and riichi bets

End game score

At the end of the game, the raw points are used to calculate the end game score. These are the two or three digit +/- numbers used to reflect a player's score. Instead of 30,000 points, a player's score may actually be displayed as +40.0.

Aotenjou

Aotenjou 「青天井」 is the practice of scoring hands without any limit imposed. This practice is rarely used, because without scoring limits, hands can produce ridiculously high point values. Naturally, that is induced by the exponential function of the basic points equation.

External links

Japanese mahjong scoring rules in Japanese Wikipedia