Mahjong exposure rules
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An exposure is a group you complete by calling a discard and lay face up on top of your rack, and you can only make one when you call. You can change it until you discard or swap a joker; after that it is locked, so you cannot add a fourth tile to an exposed pung on a later turn.
When can you expose tiles?
Only when you call a discard to finish a pung, kong, quint or larger group, or when you declare mah jongg. Groups you build from tiles you drew yourself stay hidden on your rack until you win. A hand marked C (concealed) on the card exposes nothing before mah jongg.
What can an exposure hold?
An exposure holds three or more identical tiles, built around the real tile you called, with jokers allowed for the rest. Pairs, singles and mixed groups wait until mah jongg.
- Identical tiles. The called tile plus matching tiles from your rack. Jokers may stand in for any of them.
- At least one real tile. The called discard is the real tile, so an exposure can never be all jokers.
- No pairs, singles or mixed groups. A pair, a single, a run of different numbers, a set of all four winds or a year like 2026 can only go face up when you declare mah jongg.
- One hand's worth. Every exposure on your rack must fit the same line on the card.
Can you add to an exposed pung?
Not after you discard. Until you throw your discard or swap a joker, you may add a tile from your rack to turn the pung into a kong, take a tile back, or fix a mistake. Once the discard is down, the group is locked: a fourth matching tile stays on your rack or goes to the discards. The only change still allowed is a joker swap, where any player hands in the real tile and takes the joker.
What is an invalid exposure?
An exposure is invalid when it fits no hand on the card next to your other exposures, or when it holds tiles that do not belong together. If another player can show it, your hand is dead, and the invalid group goes back to your rack, jokers included.
Where tables play it differently
- Adding later. Some casual tables let you grow a pung into a kong on a later turn. League rules do not.
- How you call. Some tables want "pung" or "kong" said out loud. Others accept "call" or the tile's name.
A worked example
You hold two 8 Craks and a joker. West discards an 8 Crak. You call it and lay out a kong:
Before you discard, you notice the line you are chasing wants a pung of 8 Craks and a kong somewhere else. You take the joker back, leave three 8 Craks face up, and then discard. Three turns later you draw the fourth 8 Crak. The pung is locked, so it stays on your rack or goes to the discards.
Common questions
Can you expose tiles you drew yourself?
No. You expose a group only when you call a discard to finish it, or when you declare mah jongg. Groups you build from the wall stay on your rack.
Can an exposure be all jokers?
No. An exposure is built around the discard you called, and that tile is real. You may hold a group of all jokers hidden on your rack, but you cannot expose one.
Can you expose NEWS or a year in mahjong?
Not before mah jongg. A set of four different winds or the digits of a year are singles, not identical tiles, so you can only lay them face up when they finish your winning hand.
How many exposures can you have?
As many as the hand you are chasing allows, as long as every one fits that same line on the card. Each exposure tells the table more about your hand, so expose only what you need.
Can you change an exposure after discarding?
No. After your discard the group is locked. The only change anyone can make is swapping the real tile for a joker in it.