Mahjong: Luck vs Skill, Through the Lens of Probability

Deal luck, decision skill

Your opening 13 tiles are random, but every draw and discard is a decision under uncertainty. Strong players win more over many hands even though any single hand can be decided by one unlucky tile.

Think of mahjong like poker: the cards dealt are luck, but folding, attacking and reading opponents are skills that compound over hundreds of hands.

Tile efficiency is measurable

Hands with many dual-purpose waits reach tenpai faster. Shanten counting — how many steps your hand is from ready — is the core of efficiency. Playing to lower shanten on every turn is the fastest beginner improvement.

This site shows your tenpai status and lets you compare discards against the AI, so you can see which choices keep the hand efficient.

Reading the table

Discards reveal intent: a player suddenly discarding honors is likely tenpai. Late-game, the safest tiles are genbutsu (their discards) and suuji. Defense converts a losing position into a non-losing one — the highest-leverage skill in riichi.