When to riichi: almost always, and right away

Your closed hand has reached tenpai, and the tile in your fingers can go down sideways or flat. Most of the time it should go down sideways: declare riichi on this turn, even on a bad wait. The times to stay quiet fit on one short list, and you can check each one at the table.

A quick reminder from the tenpai and furiten lesson: riichi needs a closed tenpai, 1,000 points for the stick, and at least four tiles left in the wall. The riichi page has every rule. A closed tenpai you don't declare is dama (damaten, a silent tenpai).

What riichi buys and what it costs

Riichi buys you four things.

• A yaku. A winning hand needs at least one yaku (What is a yaku?), and riichi gives one to any closed tenpai, whatever its shape.
• A han. Below mangan, each han roughly doubles the payment. A plain closed tanyao hand on a kanchan (middle wait) pays 1,300 by ron. With riichi it pays 2,600.
• Ura dora and ippatsu. A riichi winner also counts the ura dora, read from the tiles under the dora indicators. A win within one go-around of the declaration, with no call in between, adds a han for ippatsu.
• Pressure. Opponents who aren't close to tenpai fold against a riichi. A folding hand isn't racing yours anymore.

It costs you four things too.

• 1,000 points. The stick comes back when you win. Another player's win takes it, and a drawn hand leaves it on the table for the next winner.
• A locked hand. You can't change the wait or add value. Every tile you draw that doesn't win goes straight to your discards.
• Your defense. If another player declares after you, you can't fold.
• Information. Everyone knows you're tenpai, and careful players hold the tiles that look dangerous to you.

In most hands the trade favors riichi. The costs bite when the hand is already big or the wall is nearly empty, which is where most exceptions live.

The default: riichi now, bad wait or not

When your closed hand reaches tenpai and nobody has declared yet, riichi on that discard. Chasing someone else's riichi waits for Tenpai against a riichi.

Bad waits too. A kanchan, a penchan (edge wait), and a tanki (single wait) are one-sided waits, on one tile kind each, and they still win plenty of riichi hands. In the site's riichi wait win rate data, from Tenhou's top room (Houou), a riichi declared at turn 8 wins 52% to 57% on a ryanmen (two-sided wait), 41% on a one-sided wait for a 2 or 8, and 33% on a one-sided wait for a 5. Turns count from zero there and in the rest of this lesson: turn 8 is your ninth discard. The bad wait wins less often, and riichi doubles what those wins collect. The wait win rate tool looks up any wait. Older advice said to keep a cheap hand on a bad wait quiet. Retire it.

Right away. The same data shows a two-sided riichi declared one turn after tenpai wins 3 to 4 percentage points less. Waiting for a draw that improves the hand leaks the same way.

This pinfu hand wins on 2s and 5s: 8 tiles, none visible. Six tiles would improve it: a 4m adds tanyao once you cut the 1m, and a red 5m or red 5p adds a dora. Only your own draw brings those six, while any player's 2s or 5s wins. Dama, that win pays 1,000. Riichi now and it pays 2,000, before ura dora or ippatsu.

The same default as dealer

Nothing changes when you deal, except the payoff. The dealer collects 1.5 times what a non-dealer does (the scoring lesson), while the stick still costs 1,000. A riichi-only ron on a kanchan pays the dealer 2,000 against 1,300.

The dealer's riichi wins about as often: 56.8% against 55.8% for a non-dealer, on a 1-4 wait at turn 8 in the same data. The edge is the payment, plus the next hand: a dealer who wins keeps the deal (How a game works). The list below quotes non-dealer prices.

Dama needs a yaku

Without riichi, a closed hand needs a yaku of its own to win by ron. With none, dama wins only by tsumo, through menzen tsumo (the yaku for a closed self-draw).

Say the dora is the . This hand holds three dora: two 7p and the red five. It has no yaku. The 1m, 9p, and 1s rule out tanyao, and the kanchan on 2s rules out pinfu. Stay quiet and a discarded 2s is a tile you can't take. Declare and the same 2s pays a mangan, 8,000: riichi plus three dora is 4 han 40 fu.

So the dama question only comes up when the hand already has a yaku, like tanyao, pinfu, yakuhai, or seven pairs.

The short list of times to stay quiet

Here's my list:

1. A mangan, from turn 12 on. The hand pays a mangan (8,000) without riichi and waits on number tiles. Earlier, riichi a two-sided wait; a bad wait can stay quiet at any turn.
2. A 6,400, from turn 9 on. Same idea, a smaller hand, an earlier switch. A two-sided 3,900 or 5,200 is a riichi at any turn before the last few.
3. A win that already settles your placement. Late in a game, when a quiet win lifts you past the player above, riichi's extra points change nothing. Stay quiet: a silent hand wins more easily and can still fold. Later in the course, Play for placement and All Last decisions show how to tell.
4. A seven-pairs wait on a terminal or honor dora. Riichi tells everyone to hold that dora. Seven pairs or toitoi showed what that costs.

A dama haneman or bigger stays quiet too: 6 and 7 han both pay a haneman, and a yakuman can't go higher. Treat a 7,700 (4 han 30 fu) like a mangan: riichi adds only 300 to its ron, but a riichi tsumo or one ura dora makes it a haneman.

From your third row of discards (turn 12 on), a wait with one copy left or none stays quiet too: riichi would stake 1,000 and your fold on a long shot (When to refuse tenpai).

Why the turn matters for the first two: the data post makes a rough comparison of the same waits with and without riichi, in hands holding several dora. At turn 8, a two-sided wait on 1 and 4 wins 57% with riichi and 67% as dama. Early, riichi's han, ura dora, and ippatsu are worth more than those 10 points. But that value pays only on a win, and wins thin out: the same riichi wins 35% at turn 14. The costs don't shrink. A bad wait thins out sooner: at turn 8 the one-sided waits above win 33% to 41%, like a two-sided riichi between turns 11 and 14.

The shuhari post saves items 1 and 2 for Mahjong Soul's Master rank. Below it, riichi them anyway, as in your first ranked games: the usual leak runs the other way, dama on a hand that isn't on the list, like a 2,000-point tenpai with one dora. The rest of the list holds at any rank: riichi there gains little or costs the win. If you're not sure a hand is on the list, riichi.

Practice

Each problem gives the turn, the yaku, and the dora. Count the value where it isn't given. You're not the dealer in any of them. Below Master, treat the answers that rest on items 1 and 2 as the play to grow into.