Chinese Official Mahjong · 6 pt

Half Flush in Chinese Official Mahjong (MCR): Points, Reaching 8 and Odds

In Chinese Official Mahjong, Half Flush (混一色) is worth 6 points: when you win, the whole hand — tiles in hand plus every chow, pung and kong you exposed — uses only one numbered suit (characters, dots or bamboo) plus honor tiles. With no honors it's Full Flush; with only honors it's All Honors.

The rules for Half Flush

• Only one suit of numbered tiles: all characters, all dots or all bamboo — none of the other two suits
• At least one honor tile (winds or dragons), as a pung or as the pair
• Chows, pungs and kongs are allowed; the hand doesn't need to be concealed
• Flowers don't affect it; each scores 1 point separately (not toward the minimum)

How to get Half Flush to 8 points

A Half Flush already holds honors, so the smoothest top-up is to make an honor pung:

Two 1-pointers also work: a pung of someone else's wind (not the prevalent or your seat wind) is a Pung of Terminals or Honors, plus one of Short Straight, Pure Double Chow, Edge Wait, Closed Wait, Single Wait or Self-Drawn.

What Half Flush no longer counts

• One Voided Suit (1 point): a Half Flush always lacks two suits, so under the non-repeat rule it's not counted again.
• A Half Flush has honors, so No Honors and All Simples can't apply anyway.

The other way round, All Green (88 points) with the Green Dragon is itself a Half Flush, so Half Flush is not counted on top. Honor fan don't absorb it: Big Four Winds or Little Three Dragons plus one suit still score Half Flush separately.

Scoring examples

These hands are scored live by the site's scoring engine — exactly as in the game.

How it relates to other fan

• Full Flush: one suit too, but no honors. Discard the honors from a Half Flush one by one and it becomes a Full Flush.
• All Pungs: honors can only be punged, not chowed, so a Half Flush often ends up All Pungs — two 6-pointers clear 8 easily.
• Dragon Pung, Prevalent Wind, Seat Wind: the usual top-ups, 2 points each.
• Seven Pairs: seven pairs in one suit plus honors score both, 30 points together.
• Little Three Dragons, Little Four Winds, All Terminals and Honors: these honor-heavy hands are often a Half Flush at the same time.

Half Flush odds

Tiles of one suit plus honors in the opening hand

In a 13-tile opening hand, the strongest suit plus all honors comes to 9 or more tiles about 23% of the time, 10 or more about 6.8%.

Source: 1,000,000 random 13-tile deals (flowers already replaced).

Playing normally vs forcing Half Flush

In 4,000 hands of the site's AI playing normally, Half Flush appears in 3.2% of wins, and those wins average 13.8 points.

A second experiment: each hand, the player whose opening has the most "one suit plus honors" must go for Half Flush — discard the other two suits, only claim that suit and honors, pick waits that reach 8 points, and never win without the flush — while the other three play normally.

Source: computer play on this site. Forcing: 2,000 hands where the seat with the best start forced Half Flush while the other three played normally; normal play: 4,000 hands of four normal-level computers. Points use MCR scoring (self-draw: each pays fan + 8; discard: the discarder pays fan + 8, the others 8 each).

The verdict: with 10 or more tiles of one suit plus honors, forcing Half Flush does slightly better than normal play; with 9 or fewer it doesn't pay.

• Forcing it from 9+ tiles succeeds about 23% of the time, average result −1.2; the AI playing the same openings its own way averages ±0.0, and finishes a Half Flush only 2.5% of the time.
• From 10+ tiles, forcing succeeds about 29%, average +2.5 (normal play +1.7).
• Forced Half Flushes that succeed average 15.6 points and are won on draw 12.3 on average.
• Rows highlighted in green are the openings where forcing beat normal play.

When to go for Half Flush

• One suit plus honors is 9+ tiles: you're only a few tiles away; see the numbers above.
• You hold an honor pair: Red, Green, White, or your own seat or prevalent wind — punging it adds 2 points, exactly what Half Flush needs.
• Know where the 8th point comes from: Half Flush with one Short Straight or one Pung of Terminals is exactly 8; when ready, check that every winning tile reaches 8.
• Others will read it: two exposed sets of one suit and none of that suit in your discards tell the table you're on a flush, and they'll hold those tiles.

When to give up: past halfway through the wall with three or more off-suit tiles still in hand, or when the honors you need are already discarded. To practise the call, play MCR online against the AI — scores are worked out for you.

Half Flush in other mahjong styles

• Taiwanese Mahjong: 4 tai (Taiwanese Mahjong Half Flush)
• Japanese Riichi Mahjong: honitsu, 3 han concealed, 2 han open (Riichi yaku list)
• Hong Kong Mahjong: 3 fan (Hong Kong Mahjong fan table)

FAQ

How many points is Half Flush?

Half Flush is worth 6 points in Chinese Official Mahjong. With the 8-point minimum it can't win alone; you need at least 2 more, most often from a dragon or wind pung.

Can you chow in a Half Flush?

Yes. MCR doesn't require it to be concealed — exposed sets just have to be that suit or honors. Staying concealed adds Concealed Hand, 2 points.

How much is Half Flush with All Pungs?

Half Flush 6 plus All Pungs 6 is 12 points, already past 8; dragon or wind pungs and concealed pungs add more.

Does Half Flush also score One Voided Suit?

No. A Half Flush always lacks two suits, so One Voided Suit (1 point) is not counted again.

Related fan

Full Flush 24 pt Every tile from a single suit for 24 points. Examples, the non-repeat rules, Half Flush vs Full Flush, and how many suited tiles you need. All Pungs 6 pt Four pungs and a pair for 6 points — short of the 8-point minimum. How to top it up and what it stacks with. Dragon Pung 2 pt Each pung of Red, Green or White is 2 points (no extra terminal-pung point); two become Two Dragon Pungs, three Big Three Dragons.