Japanese Mahjong scoring rules


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 period 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.
There are two criteria in 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. Fu is the value of melds, waits and "going out".

Steps of calculation

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

The total number of han of all the kinds of yaku in the hand is summed up. Each dora 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 or chītoitsu, 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 as a unit and it is not necessary to calculate fu or [|basic points].

Counting fu

Fu is counted in the order below and then rounded up to the tens. There may be variations of rules for counting it.
and yield more than mangan and there is no need to calculate basic points.
  1. A winning hand is automatically awarded 20 fu. This is called fūtei.
  2. Ten fu are added if one wins by claiming a discarded tile with a closed hand. This is called menzen-kafu.
  3. Add fu of the melds and the pair.
  4. Add fu according to how the waiting was.
  5. Add two fu if one wins by self-draw. This way of winning is called tsumo. However, if the winning hand includes a yaku of no-points hand, in most rules the two fu are not awarded and the hand is counted as a total of 20 fu.
  6. Winning with yaku which include seven pairs is counted as 25 fu altogether. The value is not rounded up to the tens. Some rules say seven pairs has 50 fu and one han, especially in the Kansai region.
  7. As an exception, if one wins by claiming a discard with an open hand with melds and waits to which no fu is awarded, the hand is not 20 fu but counted as a total of 30 fu. This is the fu for an open pinfu.

    Fu of melds

The list for the third step:

Fu of waits

The list for the fourth step:
ryanmen-machi
0 fu
kanchan-machi
2 fu
penchan-machi
2 fu
tanki-machi
2 fu
shanpon-machi
0 fu
However, a triplet is made, so 2, 4, or 8 fu of melds is added

Calculating basic points

The basic points of a hand is calculated as follows:
The actual points given are rounded up to the nearest 100. 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.

Example calculations

Example 1: The player on the right of the dealer goes out by self-draw. The winner's hand is closed and has a closed triplet of Souths. The player also has two Whites as the pair and the winning tile is a White. The yaku are "self-pick" and "honor tiles", and they yield a total of two han. The sum of fu is 20 + 8 + 2 + 2 + 2 = 34 fu, rounded up to 40 fu.
The basic points are thus 40 × 2 = 640. The dealer pays the winner 640 × 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 + 10 + 8 + 2 + 2 = 42 fu, rounded up to 50 fu.
The basic point is thus 50 × 2 = 400. The discarder pays the winner 400 × 4 = 1,600 points. The other two players pay the winner nothing.

One han 110 fu

It is possible for a hand to have one han with 102 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.
, closed, closed, winning by a discard.
The hand has yakuhai of one han with 20 fu of fūtei, 10 fu of menzen-kafu, 32 fu of ankan, 32 fu of ankan, four fu of minkō, 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.

Scoring table

Since the method of calculating a winning hand's score in mahjong is quite tedious, many players refer to a scoring table to look up the final score of a hand. 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 are derived from the scoring equation and procedure with each corresponding han and fu values.
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.
The reason why there are no scores in the 1 han 20 fu cell is that such a hand is impossible. The only 20 fu hands are the no-points hand where the winning tile is self-drawn. However, since a no-points hand must be closed, it makes winning via a self-drawn tile automatically add 1 han yaku of self pick to the hand. Therefore, a 1 han 20 fu hand cannot exist. A seven pairs hand is fixed at 25 fu. Since the hand is always closed, it adds 1 han of self pick when won by self-draw.

Mangan

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. 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 × 2 = 880 < 2,000.
Two han cannot reach mangan because 110 fu × 2 = 1,760 < 2,000.
When a hand has 120 fu or more, it always has some yaku of three han or more.

Exhaustive draws

In 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 nōten hands. After each exhaustive draw, the counter increases by one.

Tenpai

Tenpai 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 nōten.
Players must show their hand to verify that it is tenpai when a hand is a draw and if they declared rīchi or if they declare tenpai. If a hand with rīchi declaration is nōten, a chombo penalty is imposed. In some cases, a player who didn't declare rīchi can declare nōten even when the hand is tenpai to keep their hand concealed.

Point exchange

Players receive or pay points called nō-ten bappu in the following way, when a hand ends in an exhaustive draw:
In most rules when a dealer's hand is nōten, 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 nōten.

Counters

When there are counter sticks on the table, winners get bonus points calculated by multiplying 300 by the number of those counters. Honba is a unit of continuous dealer wins and draws, and to be exact, hon is a unit of numbers of some bars and so on, and ba 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 or, the dealer remains the same. In the case of, 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 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 instead of renchan, and happens for example by their nōten in the case of a draw.
In a state of n counters, when a player wins a hand by self-draw, 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, the player gets a bonus of n × 300 from the discarder.
Example:
Optionally, a rule may restriction of ryanhan-shibari. 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, 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 rīchi and invalid kan after rīchi, they are caught only after draws or winning declarations by players who declared the rīchi. If other players happen to win the hand, then the infractions are not revealed and therefore made null and void. Any rīchi bets are returned to the players after the end of a chombo hand.

Final points and place

After the game is finished, the points of each of the three players other than the winner is rounded off to the nearest 1,000. The winner's points are the difference between 120,000 and the total of these three players' points. The number of points is divided by 1,000, and 30 is finally subtracted from it. The sum of these final points is always zero. In most cases there are additional points transferred based on the players' final places.
Example: The initial points are 25,000 each. A : 43,600, B: 14,500, C: 15,400, D: 26,500, and rounded off to B:15,000, C:15,000, D:27,000. The number of the winner's points is calculated as follows irrespective of initial points: 120,000 − = 63,000. The final points and place: A:+33, D:−3, C:−15, B:−15. The 1st place is also counted like: + + = +33.

Optional scoring rules

Wareme

In the optional rule wareme, 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 when the player is the dealer.