Riichi Mahjong · Closed 2 / open 2

Toitoi (All Triplets) in Riichi Mahjong: Han, Examples and Odds

In riichi mahjong, Toitoi (toitoihou, "all triplets") is a 2-han yaku: your winning hand is four triplets (three identical tiles) or quads, plus a pair. It stays 2 han even after you pon, with no open-hand reduction, which makes it one of the go-to yaku for calling.

The rules for Toitoi

• All four sets are triplets or quads: called with pon, drawn yourself, open or closed kans all count
• Not a single sequence, so you cannot chi
• The pair can be any tile
• Any suits and honors
• 2 han closed or open

How Toitoi waits

Shanpon: two pairs, waiting on either

You hold two pairs and win when either tile is drawn or discarded. Two tiles to wait on — the most common Toitoi wait.

Tanki: four triplets done, waiting for the pair

All four triplets are complete and one tile waits for its partner. Only one tile wins, but you can pick an honor or another tile that's likely to be discarded.

How Toitoi is scored

The yaku, han, fu and points below are computed live by the same scoring code the game uses.

Common combinations:

How it relates to other yaku

• Sanankou: three triplets you drew yourself, 2 han, stacks with Toitoi. A triplet completed by ron doesn't count as concealed.
• Suuankou: four triplets all drawn yourself, nothing called — a yakuman. A closed Toitoi won by tsumo is almost always Suuankou; won by ron on a shanpon wait, the ron'd triplet isn't concealed, so it's sanankou + Toitoi.
• Chinitsu: four triplets all in one suit score both Toitoi and chinitsu.
• Honitsu and yakuhai: honors can only be called with pon, never chi, so honitsu and yakuhai hands often turn into Toitoi.
• Honroutou: a hand of only terminals and honors is always Toitoi or chiitoitsu in shape.

Toitoi odds

How many pairs in your starting hand

Toitoi needs four triplets and a pair, so the more pairs you start with, the better. A 13-tile starting hand has 3 or more pairs about 15% of the time, and 4 or more only 2.2%.

Source: 1,000,000 random 13-tile deals.

Is it worth forcing Toitoi?

We let computers play on this site's table: in every hand, the player with the most starting pairs had to go for Toitoi — pon only, no chi, no riichi, and no win without Toitoi — while the other three played normally. Then we compared the average result with the same starting hands played normally.

Source: computer play on this site. In each of 24,000 hands the seat with the best start forced Toitoi (no riichi, no other win); the other three played normally at normal level. Points are the hand’s gain or loss, including riichi sticks.

Toitoi is easier than chinitsu, but forcing it loses in every group.

• With 4 or more pairs, forcing it works about 23% of the time; finished hands averaged 3.9 han and 8,300 points.
• Yet the average result was +720, against +975 for the same starts played normally: pon only, no chi, no riichi and no win without Toitoi is just too slow.
• Fewer pairs make it worse: with 3 pairs, forcing it only works 13% of the time.
• When the computers play normally, Toitoi is 0.19% of all wins.

Which hands suit Toitoi

• Four or more pairs in your start, or a concealed triplet already: you're only a few tiles away.
• Yakuhai pairs: white, green, red, your seat wind and the round wind give 1 han just for the pon; with Toitoi that's 3 han or more.
• Pairs whose tiles haven't been discarded: once two copies are out, that pair can't be called with pon anymore.
• Others notice after two pons: two or three exposed triplets and no sequences tell everyone you're going for Toitoi.

When to give up: less than half the wall is left and you still need two or more sets, or someone has declared riichi while you're far away. Switch back to normal play or start defending. To practise, open a table of free online riichi mahjong — the computers play with you and count the points for you.

Toitoi in other mahjong styles

"All triplets" exists in every style, but scores differently:

• Taiwanese mahjong calls it "peng peng hu", 4 tai (Taiwanese mahjong All Pungs)
• Hong Kong mahjong: "All Pungs", 3 fan (Hong Kong mahjong All Pungs)
• Sichuan mahjong: "All Pungs", 1 fan (Sichuan mahjong All Pungs)
• Chinese Official (Guobiao): "All Pungs", 6 fan (Guobiao All Pungs)

FAQ

How many han is Toitoi?

Toitoi is 2 han. It stays 2 han when open — there's no open-hand reduction.

Can you chi for Toitoi?

No. A chi always makes a sequence, and Toitoi needs all four sets to be triplets or quads.

Is Toitoi still a yaku after calling pon?

Yes. Toitoi is a yaku by itself, so you can win after calling pon without any other yaku.

What if a closed hand becomes Toitoi?

Win it by tsumo and all four triplets are concealed — that's Suuankou, a yakuman. Win a closed shanpon wait by ron and the ron'd triplet isn't concealed, so it's sanankou + Toitoi.

What's the difference between Toitoi and chiitoitsu?

Chiitoitsu is seven different pairs, 2 han and closed only. Toitoi is four triplets and a pair, and you can call pon. Both are worth considering when you have lots of pairs.

Related yaku

Sanankou Closed 2 / open 2 Three self-drawn triplets, 2 han even when open. The shanpon-ron trap, why the fu are high, and how it differs from suuankou. Chinitsu Closed 6 / open 5 Every tile from one suit — 6 han closed, 5 open. Examples, chinitsu vs honitsu, and how many suited tiles you need. Yakuhai Closed 1 / open 1 A triplet of dragons, seat wind or round wind — 1 han, even when called. Double wind, atozuke and one-sided waits.