Japanese mahjong scoring rules are used for Japanese mahjong, a game for four players common in Japan. The rules were organized in the Taishà  to Shà Âwa 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.
The payment to the winner of a hand is calculated as follows:
In the case of a draw, points are transferred according to the nà Â-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.
The total number of han (é£Â) of all the kinds of yaku (å½¹; winning hand) in the hand is summed up. Each dora (ãÂÂã©) 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 (äºÂçÂÂå£) or chëtoitsu (ä¸Â対åÂÂ), but since ryanpeikou is three han where chëtoitsu 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 (æºÂ貫) as a unit and it is not necessary to calculate fu (符) or basic points.
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 (chëtoitsu, ä¸Â対åÂÂ) is counted as 25 fu altogether. No more fu can be added and the value is not rounded up to the tens. (Some rules list seven pairs as 50 fu and one han, especially in the Kansai region.)
Any other winning hand starts with 20 fu, and is then checked for the following bonuses:
<ol> <li>An additional +10 fu is added if the winner had a closed hand and won by claiming a discarded tile.</li>
<li>Fu is added for each component of the hand (each of the four melds and the one pair). 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):
</li>
<li>If the winning tile was either part of the pair, the middle tile of a sequence, or a simple tile in a sequence also containing a terminal, the hand is awarded +2 fu.</li>
<li>If the winning tile was self-drawn, and the hand does not have the pinfu yaku, +2fu is awarded.</li>
<li>At this point, if the hand has not accumulated any fu past its starting balance of 20, and it is an open hand, it is awarded +2fu.</li>
<li>Finally, if the running tally of fu is not a multiple of 10, it is rounded up to the next highest multiple of 10. This is the final result.</li> </ol>
The method of calculating a winning hand's score from han and fu is somewhat tedious, so it is easier to use a pre-computed lookup table. Expert and professional players have this table memorized and can thus tell the value of a hand at a glance. Each of the table's point values is derived from the scoring equation and procedure with each corresponding han and fu value.
The formula itself is fu ÃÂ 2<sup>(2+han)</sup>. This produces the hand's "basic" points. If the dealer wins, they are owed 6 ÃÂ basic; a non-dealer winner is owed 4 ÃÂ basic. If it was a win by discard, the player who discarded the winning tile is fully liable. Otherwise, for a self-drawn win, all three other players split the bill (evenly if the dealer won; otherwise, the dealer pays half, and the other two players pay a quarter each). All payments are then rounded up to the nearest hundred. Even if the values of han and fu are the same, the points received for self-draw wins often slightly deviate from those received for discard wins because of rounding.
To use the table, simply look up the values that correspond to the han and fu counts of the hand. The top numbers in each cell indicate the payout from a player who discards a winning tile. The numbers in brackets indicate the payout for each player in the event the winning tile is self-drawn. If the winner is the dealer, each player pays the same amount. If the winner is a non-dealer, then the other two non-dealers pay the smaller number, while the dealer pays the larger number.
When it is clear that a hand reaches basic points of more than 2,000, it is limited to full basic points of 2,000 and called mangan (æºÂ貫). A hand of five han or more is always counted as a multiple of mangan. In those cases, there is no need to calculate basic points.
One han cannot reach mangan because 110 fu ÃÂ 2<sup>(2+1)</sup> = 880 < 2,000. (With one han, 110 fu is the maximum.)
Two han cannot reach mangan because 110 fu ÃÂ 2<sup>(2+2)</sup> = 1,760 < 2,000. (With two han, 110 fu is also the maximum.)
When a hand has 120 fu or more, it always has some yaku of three han or more.
Example 1: The player on the right of the dealer goes out by self-draw. (The dealer's wind is always East in Japanese rules.) The winner's hand is closed and has a closed triplet (ankà Â) of Souths. The player also has two Whites as the pair (toitsu) and the winning tile is a White. The yaku are "self-pick" (menzenchin-tsumo-hà Â) and "honor tiles" (yakuhai), and they yield a total of two han. The sum of fu is 20 (fà «tei) + 8 (a closed triplet of Souths) + 2 (a pair of Whites) + 2 (pair wait) + 2 (self-draw) = 34 fu, rounded up to 40 fu.
The basic points are thus 40 ÃÂ 2<sup>(2+2)</sup> = 640. The dealer pays the winner 640 ÃÂ 2 = 1,280, rounded up to 1,300 points. The other two non-dealers pay the winner 640, rounded up to 700 points.
Example 2: The same player goes out by the same hand, except this time the winning tile was discarded by the player on the right. The resulting hand has one han of honor tiles. The number of fu is 20 (fà «tei) + 10 (ron with a closed hand) + 8 (a closed triplet of Souths) + 2 (the pair of Whites) + 2 (pair wait) = 42 fu, rounded up to 50 fu.
The basic point is thus 50 ÃÂ 2<sup>(2+1)</sup> = 400. The discarder pays the winner 400 ÃÂ 4 = 1,600 points. The other two players pay the winner nothing.
It is possible for a hand to have one han with 102 fu (rounded up to 110 fu) if the rules allow a pair to have four fu when it is made of wind tiles that are both the seat wind and the prevailing wind. Some rules consider that such a pair is still worth two fu, making the hand have exactly 100 fu.
An example of a hand that has one han with 110 fu (winning by a discard):
The hand has yakuhai of one han with 20 fu of fà «tei, 10 fu of menzen-kafu, 32 fu of ankan, 32 fu of ankan, four fu of minkà Â, and four fu of toitsu. East is both the player's seat wind and the round's prevailing wind in this case. This is the largest amount of fu that a hand with one han can have.
On plenty of occasions, a hand ends with all tiles drawn and the 14 tiles in the dead wall remain. Yet, no player wins the hand. This is the exhaustive draw. In this case, points may be exchanged barring any tenpai hands vs nà Âten hands. After each exhaustive draw, the counter increases by one.
Tenpai (è´çÂÂ) means one tile short of a winning hand. To be tenpai, a hand does not need any particular yaku partly because winning by the last discard is yaku itself. When a hand is not tenpai, the situation is called nà Âten (ãÂÂã¼è´: nà  is English "no" and ten for tenpai).
Players must show their hand to verify that it is tenpai when a hand is a draw and if they declared rëchi or if they declare tenpai. If a hand with rëchi declaration is nà Âten, a chombo penalty is imposed. In some cases, a player who didn't declare rëchi can declare nà Âten even when the hand is tenpai to keep their hand concealed.
Players receive or pay points called nà Â-ten bappu (ãÂÂã¼è´罰符; fu of penalty for nà Âten) in the following way when a hand ends in an exhaustive draw:
In most rules when a dealer's hand is nà Âten, the dealer changes and the game wind may change. But if it's the last hand of the last round, in some rules, a game does not end if the dealer declares nà Âten.
Nagashi mangan is an uncommon special outcome to an exhaustive draw which occurs when a player has met the following conditions:
If this occurs, the tenpai/nà Âten point exchange is canceled and the player responsible is instead paid by the others as though they had won with a self-drawn mangan.
When there are counter sticks (honba) on the table, winners get bonus points calculated by multiplying 300 by the number of those counters. Honba (æÂŒʫ) is a unit of continuous dealer wins and draws, and to be exact, hon (æ¬) is a unit of numbers of some bars and so on, and ba (å ´) 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:
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 (é£èÂÂ) 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èÂÂ) instead of renchan, and happens for example by their nà Âten 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 à100 points from each of other three players for a total of n à300, and when a player wins by claiming a discard (ron, æ Â), the player gets a bonus of n à300 from the discarder.
Example:
Optionally, a rule may add the restriction of ryanhan-shibari (äºÂé£Âç¸ÂãÂÂ; 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.
Under the rule of chombo (ãÂÂã§ã³ãÂÂ, é¯å or å²åÂÂ), 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:
In game infractions, such as the false rëchi and invalid kan after rëchi, they are caught only after draws or winning declarations by players who declared the rëchi. If other players happen to win the hand, then the infractions are not revealed and therefore made null and void. Any rëchi bets are returned to the players after the end of a chombo hand.
Other settings for chombo apply point penalties after the game's conclusion. This is especially the case under tournament settings. Under this method, players do not benefit with any point gains. Instead, the infracted player solely takes a point deduction. The deduction may be set to any specified number.
At the end of the game, the final scores may be calculated. Under casual game settings, this calculation is not necessary. However, under more formal settings, it may be required. This calculation takes the game's scores and adjusts them according the setting of oka and uma, which were predetermined before the game. The calculation for each player is as follows:
End score = ((End points + Oka - Target)/1000) + Uma
Point settings may vary but are always determined prior to the beginning of a game. In particular, different mahjong platforms utilize their own settings to uma.
In the optional rule wareme (å²ãÂÂç®, ã¯ã‹¡; fissure, split), the player in front of whom the wall was split to indicate the end of the dead wall, acquires and pays double the normal points. They are doubled after the points for counters are added. It is often especially called oya-ware (親å²ãÂÂ; parent's wareme) when the player is the dealer.