What is soap in mahjong?
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Soap is the White Dragon, the plain framed tile that looks like a bar of soap, and every set has four of them. It does two jobs: it is the dragon that goes with the Dots suit, and it stands in for zero wherever the card prints a 0, as in a year like 2026.
Why is it called soap?
On many sets the White Dragon is a blank white face inside a thin border, and that looks like a bar of soap. Some sets print a design on it instead; it is still the soap. Some sets also come with extra blank tiles. Those are spares, not soaps.
How do you use soap?
Soap plays two roles, and the card tells you which one a hand wants.
- As a dragon. Each suit has its own dragon: Red goes with Craks, Green with Bams, and Soap with Dots. On the card, a dragon printed in the same color as a group of numbers belongs to that suit. Like the other dragons, soaps form pairs, pungs and kongs.
- As zero. Wherever the card shows a 0, use a soap. A zero has no suit, so the soap works next to numbers in any suit. It is only a zero where the card prints one; it never fills a run or stands in for some other number.
Rules that trip players up
- Soap is not wild. It only counts as a dragon or a zero.
- A year spelled one tile per digit needs a real soap. Each digit there is a single, and jokers never fill a single.
- A group of three or more soaps can take jokers, like any other pung or kong.
- Only four exist. A pair of soaps or a year zero needs real tiles, so once three soaps are showing elsewhere on the table, those hands are gone.
Where tables play it differently
- Tile designs. Sets draw the White Dragon in different ways. Whatever yours shows, the tile with the plain frame or the White Dragon mark is the soap.
- Blank tiles. A few home groups use blanks as house-rule wild tiles. That is not part of the League game.
- Other styles. The zero role belongs to the American card. In Chinese and other styles the White Dragon is only a dragon.
A worked example
Here a soap is a zero inside a Crak year:
Because zeros have no suit, the soap does not break the one-suit look. Now a different teaching rack, where soaps are the Dots dragon:
If the card prints a line like this in one color, the soaps are the matching Dots dragon, and a Red or Green Dragon would not fit. Either pung could take a joker; a single soap in a year could not.
Common questions
Is soap the only 0 in mahjong?
Yes. In American mahjong the soap, or White Dragon, is the only tile used as a zero. There is no number 0 tile in the suits.
What suit is soap in mahjong?
As a dragon, soap belongs to Dots. As a zero, it has no suit and goes with numbers in any suit.
How many soaps are in a mahjong set?
Four, like every other dragon. A set has twelve dragons in all: four Red, four Green and four Soap.
Can a joker replace a soap?
Only inside a group of three or more soaps. A soap used as a single zero in a year, or in a pair, must be the real tile.
What suit is the red dragon in mahjong?
Craks. The Green Dragon goes with Bams, and the soap goes with Dots.