Japanese mahjong scoring rules

thumb|Japanese point sticks, used in a manner similar to [[poker chips]]

Japanese mahjong scoring rules are used for Japanese mahjong, a game for four players common in Japan. The rules were organized in the Taishō to Shōwa periods as the game became popular.

The scoring system uses structural criteria as well as bonuses. Player start scores may be set to any value. Usually, it is set to 20,000 to 30,000 points. Scores are counted using sticks of 10,000 points, 5,000 points, 1,000 points and 100 points. A game often ends when all the points of a player are lost, which is a situation called hakoten, dobon, buttobi, etc. However, some settings allow the game to continue, even if a player's score dropped below zero.

There are two criteria for determining the winning points: han and fu, which correspond to a points table. Han is the unit for the value of yaku, which are particular patterns or conditions of a hand, as well as dora, which are tiles given bonus points for the round or as marked on the tile (red fives). Fu is the value of melds, waits and "going out". Hands with enough fu and/or han may be considered limit hands; limit hands use predefined values to determine the winning points.

Steps of calculation

The payment to the winner of a hand is calculated as follows:

:1. Counting han (飜)

:2. If it is five han or more, it is mangan (満貫) or more and the calculation of basic points is omitted

:3. Counting fu (符)

:4. If it is clear that the han and fu yield more than mangan, the calculation of basic points is omitted

:5. Calculating the basic points based on the fu and han

:6. Multiplying the basic points depending on whether the winner is the dealer or non-dealer, and whether the hand is won by tsumo or ron

:7. Adding bonuses based on the number of counters

:(8. Adjusting the payment by the wareme rule)

In the case of a draw, points are transferred according to the nō-ten bappu rule. In the event of a penalty, such as claiming a win with an illegal hand, then points are transferred via the chombo rule.

Counting han

thumb|[[Japanese Mahjong yaku|Yaku table]]

The total number of han (飜) of all the kinds of yaku (役; winning hand) in the hand is summed up. Each dora (ドラ) increases the han value of a hand. Dora are not regarded as yaku, and no hand can be won without a yaku even if there are some dora tiles.

If there is more than one way to arrange the winning hand, the arrangement with the highest han is used. For example, a hand could be either ryanpeikou (二盃口) or chītoitsu (七対子), but since ryanpeikou is three han where chītoitsu is two han, ryanpeikou should prevail. Some yaku have their han value reduced by one if the hand is not closed.

If a hand has five han or more, it is always counted by mangan (満貫) as a unit and it is not necessary to calculate fu (符) or basic points.

Counting fu

Fu (符) or minipoints (EMA EU) are counted in the order below and then rounded up to the tens. There may be variations of rules for counting it. Three han with 70 fu or more and four han with 40 fu or more yield more than mangan and there is no need to calculate basic points.

Winning with yaku which include seven pairs (chītoitsu, 七対子) is counted as 25 fu altogether. No more fu can be added and the value is not rounded up to the tens.). Different melds are worth different amounts of fu points; the sum value of all five components are awarded. The value of each component is listed in this table (with examples for each):

{| class="wikitable" style="text-align: center;"

|+ Fu from melds and pairs

| +2 fu

! Open triplet of honors or terminals

| +4 fu

! Closed triplet of simples

| +4 fu

! Closed triplet of honors or terminals

| +8 fu

! Open quad of simples

| +8 fu

! Open quad of honors or terminals

| +16 fu

! Closed quad of simples

| +16 fu

! Closed quad of honors or terminals

| +32 fu

! Pair of dragons, the seat wind, or the round wind

| +2 fu

! Any other pair

| +0 fu

|}</li>

<li>If the winning tile was either part of the pair, the middle tile of a sequence, or a simple tile

Nagashi mangan

thumb|Nagashi mangan at draw: all of the winner's discards were terminals or honors.

Nagashi mangan is an uncommon special outcome to an exhaustive draw which occurs when a player has met the following conditions:

All of their discards were of terminals and/or honors.
None of their discards were taken by others to form open melds.
Their hand was closed (it does not matter if it had tenpai).

If this occurs, the tenpai/nōten point exchange is canceled and the player responsible is instead paid by the others as though they had won with a self-drawn mangan.

Counters

When there are counter sticks (honba) on the table, winners get bonus points calculated by multiplying 300 by the number of those counters. Honba (本場) is a unit of continuous dealer wins and draws, and to be exact, hon (本) is a unit of numbers of some bars and so on, and ba (場) means a scene or a situation.

The dealer keeps count of the number of continuous dealer wins and draws by placing point sticks on the table. While point sticks are usually used for scoring, here they are used merely as counters, a visual aid. The initial count is zero. The number of counters increases by one when:

(1) the dealer wins a hand
(2) a hand is a draw (ryūkyoku, 流局)
(3) an abortive draw happens.

In the case of (1) or (3), the dealer remains the same. In the case of (2), when the dealer cannot declare tenpai, the dealer changes, but the number of counters increases regardless of whether the dealer declares tenpai. In all other cases, namely when only a non-dealer wins, the count is reset to zero.

Renchan (連荘) is a situation in which a player successively plays the dealer, and is often only caused by dealer's win or tenpai; therefore, draws are not always renchan. On the other hand, the number of honba always increases when a draw or a dealer's win occurs. If the dealer changes, it is called rinchan (輪荘) instead of renchan, and happens for example by their nōten in the case of a draw.

In a state of n counters (suppose n is a number), when a player wins a hand by self-draw (tsumo), the player gets a bonus of n × 100 points from each of other three players for a total of n × 300, and when a player wins by claiming a discard (ron, 栄), the player gets a bonus of n × 300 from the discarder.

Example:

East round, 4th rotation with 0 counters (東4局0本場). The dealer (East) wins the hand. The seat winds don't rotate. Dealer puts 1 counter on the table.
East round, 4th rotation with 1 counter (東4局1本場). Hand is a draw with the dealer not declaring tenpai. The seat winds rotate. The former dealer retrieves the 1 counter and the new dealer places 2 counters.
South round, 1st rotation with 2 counters (南1局2本場). North wins by ron (claiming a discard), getting a bonus of 600 points from the discarder. The seat winds rotate and the former dealer retrieves the 2 counters.
South round, 2nd rotation with 0 counters (南2局0本場).

Optionally, a rule may add the restriction of ryanhan-shibari (二飜縛り; literally "two-han binding"). Here, players must produce hands of two han or more from yaku when the honba count surpasses a certain number. Usually, this count is five or more.

Chombo

Under the rule of chombo (チョンボ, 錯和 or 冲和), a player is given an infraction. Point penalties vary by organizations and/or events. Typically, a player pays a penalty of the same amount as mangan to other players in most rules. A non-dealer pays 4,000 to East and 2,000 to the other two players, while a dealer pays 4,000 to each. In other times, chombo does not affect the current score of the game; and instead, the penalty is applied at the end of the game. Chombo occurs for any of the following:

Invalidly claiming a winning hand
Winning on a discard under the situation of sacred discard (furiten)
Revealing a false rīchi, that is, rīchi with a hand that is not in the state of tenpai
Closed kan after rīchi if the kan changes the hand structure (in other words a kan of a tile after rīchi is not allowed if the hand can be interpreted such that the tile is a part of a sequence)
Having more tiles than allowed (depending on the rules)
Knocking the wall over so that it cannot be recovered to the way it was before It is often especially called oya-ware (親割れ; parent's wareme) when the player is the dealer.

Notes

References

External links

European Mahjong Association's Riichi Ruleset