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.

Scoring procedure

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

1. If the hand is a yakuman, then look up the 13 han values according to dealer or non-dealer numbers
2. 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 more than 5, counting fu is no longer necessary
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, the base point calculation is based on the following equation:

Basic points = fu × 2^{(2 + han)}

After determining the basic points, factor 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.

Scoring table

Dealer

Han/Fu	20	25	30	40	50	60	70	80	90	100	110
1 han	-- --	-- --	500 1500
2 han		--
3 han							4000 12000
4 han				4000 12000
Mangan (5 han)	4000 12000
Haneman (6,7 han)
Baiman (8,9,10 han)
Sanbaiman (11,12 han)
Yakuman (13+ han)

Nondealer

Han/Fu	20	25	30	40	50	60	70	80	90	100	110
1 han	-- --	-- --
2 han		--
3 han
4 han
Mangan (5 han)
Haneman (6,7 han)
Baiman (8,9,10 han)
Sanbaiman (11,12 han)
Yakuman (13+ han)

Honba

In the event of ryokyuoku or the dealer wins a hand, the honba count increases by 1. This means, the point values for the next hand increases by a total of 300. For ron, the singular player pays the additional 300 points. For tsumo, everyone pays an additional 100 each. If the honba count continues to increase, then the honba count acts as a multiplier to the 300 points. If a seat rotation occurs, that does not involve chombo, then the honba count resets back to zero.