Winning a hand

Short answer: you win with a complete hand — usually four sets and a pair — that contains at least one yaku, taken either by drawing the tile yourself (tsumo) or from an opponent's discard (ron).

Two things must be true at once: your fourteen tiles form a complete shape, and the hand contains at least one yaku. The second rule is the one that catches every new player — let's make sure it never catches you.

The complete shape

Mahjong hand: 2 of characters, 3 of characters, 4 of characters — 5 of characters, 6 of characters, 7 of characters — 4 of circles, 5 of circles, 6 of circles — 9 of circles, 9 of circles — 6 of bamboo, 7 of bamboo, 8 of bamboo — Four sets + one pair. Sequences (runs) and triplets both count as sets.

Almost every winning hand is four sets and a pair. The two exceptions are seven pairs and thirteen orphans, each its own yaku. When you are one tile away from completion, you are tenpai:

Two ways to take the winning tile

Tsumo ツモ — you draw the winning tile yourself. All three opponents pay, split by the scoring rules.
Ron ロン — an opponent discards your winning tile and you claim it. That player pays the entire score. (This is why good players fold — see the furiten lesson for the rule that governs ron.)

The yaku rule

A complete shape with no yaku is not a winning hand. You simply may not call ron or tsumo — you sit tenpai until the hand changes or ends. This is the single most common “bug report” from new players, usually phrased as “the app won't let me win.”

The no-yaku trap

Dora do not count. A hand can hold five dora and still be worthless without a yaku — dora only multiply a hand that already has one. When in doubt, the three easiest guarantees are riichi (any closed tenpai hand), tanyao (no terminals or honors), and yakuhai (a dragon or your wind triplet).

“How did I win?” — reading your score screen

When an app announces your win, it lists the yaku, then dora, then the han/fu price. If the list says only “riichi + 2 dora”, that is exactly the anatomy: one real yaku (riichi) carrying two bonus counters. Recognizing this pattern is the moment scoring starts making sense.

Worked example: same tiles, different answer

Mahjong hand: 1 of characters, 2 of characters, 3 of characters — 4 of circles, 5 of circles, 6 of circles — 6 of bamboo, 7 of bamboo, 8 of bamboo — 5 of bamboo, 5 of bamboo — 7 of characters, 8 of characters, winning tile: 9 of characters — 123m, 456p, 678s, a 55s pair, and 78m waiting on 6m or 9m. An opponent discards the 9m.

If the hand is closed (no calls), it is pinfu: all sequences, a plain number pair, a two-sided wait. Pinfu is a yaku, so you may call ron even without riichi — 1 han 30 fu, 1,000 points for a non-dealer win. With riichi declared it is 2 han, 2,000 points.

If you had called chii to make the 123m, the hand is open. Pinfu and riichi are gone, the 1m and 9m rule out tanyao, and nothing else applies. The shape is complete but there is no yaku, so you cannot call ron — or tsumo, since menzen tsumo needs a closed hand too (a situational yaku such as haitei on the very last tile is the rare exception). Calling a win anyway is a chombo, a penalty.

Common mistakes

Counting dora or red fives as a yaku. They add han only to a hand that already has one.
Calling chii or pon without a plan. An open hand loses riichi, pinfu, and menzen tsumo; make sure a yaku such as tanyao or yakuhai is still reachable.
Treating a dragon pair as yakuhai. Yakuhai needs a triplet of the value tile; a pair gives fu, not a yaku.
Forgetting who pays. Ron: the discarder pays everything. Tsumo: all three opponents pay, and when a non-dealer wins, the dealer's share is about twice the others' (each payment is rounded up to 100).

One tile, one winner

If two players can ron the same discard, rulesets genuinely differ: some allow both wins, others play head-bump (atamahane — only the player closest in turn order wins). Agree before you start — it matters rarely, but memorably.

Next: Lesson 7 — furiten, the rule that protects the discarder.