Japanese mahjong scoring rules

Japanese mahjong features a very complex scoring system. Every mahjong hand has a value in terms of han and fu associated with them. The combination of han and fu then corresponds to values indicated from the scoring table, and/or the two numbers of han and fu factor into an equation, by which the scoring table is derived.

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

Han

Main article: List of yaku

Han 「飜」 is the main portion of scoring, as each yaku is assigned a han number. 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.

Yakuman do not have a han value. If a winning hand satisfies at least one yakuman, han and fu are not counted for the hand. Points are awarded based on the yakuman value; and 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

Main article: Fu

Fu 「符」 (pronounced as foo) takes the hand composition into consideration in terms of tile melds, wait patterns and/or win method. In addition, 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 nearest 10. One exception falls on the chii toitsu yaku, which is set to 25 fu by default. While fu may be counted for hands worth 5 han or greater, it is not necessary for human memorization.

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)}, using basic points = 2,000 if the former exceeds 2,000

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, rounded up to a full 100. The dealer in this case pays 2 × basic points, rounded up to a full 100.
• When a non-dealer wins by ron, the discarding player pays the winner 4 × basic points, rounded up.
• When the dealer goes out by tsumo, the dealer scores 2 × basic points from all players, rounded up.
• When the dealer goes out by ron, the dealer earns 6 × basic points from the responsible non-dealer, rounded up.

So finally, a hand's point value is finally expressed as:

Points = Basic points x Payment multiplier

Scoring table

Main article: 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

In the event of ryuukyoku or a dealer win, the honba or tsumibou count increases by 1 for the next hand. The dealer indicates the honba count by using 100-point sticks and placing them on the dealer indictor or on the table. If someone wins a hand and East does not, the honba count resets back to zero; and the 100-point sticks are returned to the dealer.

This count increases hand values increases by a total of 300 per honba. For ron, the discarder pays the additional 300 points. For tsumo, everyone pays an additional 100 each. These extra points are added to the hand value after the capping as mangan, haneman, etc., so a non-dealer mangan tsumo with 2 honba costs 2,200 for a non-dealer and 4,200 for the dealer.

In the case of sekinin barai, the yakuman tsumo payment is borne entirely by the discarder of the ponned tile, who also has to pay 300 per honba. On a ron, the yakuman value is split between the discarder of the winning tile and the discarder of the earlier ponned tile. Most rules have the winning tile discarder pay for all honba.

End game score

Main article: Final scores

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

Main article: 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

• 麻雀の得点計算

Japanese mahjong scoring rules in Japanese Wikipedia

• Online hand scoring calculator\