The Fourth Seat

NMJL · AMJA · Verified

American Mahjong Rules Sources & Accuracy Tests

The curated NMJL and AMJA references behind every lesson, and the automated suite that verifies tile counts, the Charleston, joker rules, and glossary on every build.

Curated References

What we cross-check against

Where references differ, the National Mah Jongg League card and rulebook take precedence for American play.

Automated Suite

What the rule-accuracy tests verify

Tile counts

The 152-tile American set is reconstructed from buildDeck() and checked against canonical totals — 108 suited, 16 winds, 12 dragons, plus 8 jokers and 8 flowers.

  • ·Core deck equals 136 tiles
  • ·Three suits × nine values × four copies
  • ·Four winds and three dragons each have four copies
  • ·Full American set sums to 152

The Charleston

The mandatory ritual and its optional extensions are pinned to the glossary so they cannot drift.

  • ·First Charleston order: right → across → left
  • ·Second Charleston is optional and reverses direction
  • ·Courtesy pass is 0–3 tiles with the player across
  • ·Agreement on the courtesy pass is not required

Glossary definitions

Every term is unique, has a short and long definition, and the rule-critical ones are spot-checked.

  • ·Jokers allowed in pung, kong, quint — never in pairs, singles, NEWS, or 2026
  • ·Pairs may never use jokers
  • ·Chow is marked as not used in NMJL play
  • ·Dragon ↔ suit pairings: Red·Crak, Green·Bam, White·Dot
  • ·Concealed hands may call only the final winning tile from a discard
  • ·Flowers are played in-group in American mahjong, not set aside

Live Check

The deck, computed in your browser

Counts below are produced from the same code that powers the practice lessons, checked against the canonical totals (152 tiles for the full American set).

Frequently Asked

Sources & accuracy, answered

What sources do you use for American mahjong rules?
We cross-check every lesson against the National Mah Jongg League (NMJL) official rulebook and card, the American Mah-Jongg Association (AMJA), and other curated references. Where references differ, the NMJL card and rulebook take precedence.
How do you keep mahjong rules accurate?
An automated rule-accuracy test suite runs against the same code that powers the lessons. It verifies tile counts (152 in a full American set), the Charleston sequence, joker restrictions, and glossary definitions on every build.
How many tiles are in an American mahjong set?
152 playable tiles: 108 suit tiles (bamboo, dots, characters), 16 winds, 12 dragons, 8 flowers, and 8 jokers. Most retail sets ship with extras and blanks for a total of 166.
What is the official Charleston order?
The first Charleston passes three tiles right, then across, then left. A second Charleston is optional and runs in the reverse order, followed by an optional 0-to-3-tile courtesy pass with the player across.
When can a joker be used in American mahjong?
Jokers may substitute in pungs, kongs, and quints, but never in pairs, singles, NEWS, or year hands like 2026. They can be redeemed off another player's exposure for the natural tile.
Is this site affiliated with the National Mah Jongg League?
No. The NMJL is the authoritative source for American mahjong rules and the annual card. We are an independent maison that cites NMJL and AMJA references and verifies the lessons against them.

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