Hong Kong Mahjong

Hong Kong Mahjong · Limit

Nine Gates (九子連環) in Hong Kong Mahjong: Limit Hand, 9-Sided Wait and Odds

Nine Gates example: 1-1-1, 2 to 8 and 9-9-9 of dots, plus a 5 dots

In Hong Kong mahjong, Nine Gates (九子連環) is a limit hand, scored Limit: with a fully concealed hand — no chows, pungs or kongs — your 13 tiles are 1112345678999 of one suit (three 1s, one each of 2 to 8, three 9s). Any tile of that suit from 1 to 9 now completes the hand, and winning on it is Nine Gates, scored at the 10-fan cap.

Nine Gates is always Pure One Suit too, already 7 fan; but a limit hand isn't added up, it's simply Limit.

Waiting with 1-1-1, 2 to 8 and 9-9-9 of dots, winning on 5 dots: Nine Gates
On this page
  1. The rules for Nine Gates
  2. How Nine Gates is scored
  3. How it relates to other hands
  4. Nine Gates odds
  5. When Nine Gates can happen
  6. Nine Gates in other mahjong styles
  7. FAQ

The rules for Nine Gates

The 9-sided wait

Add any tile of the same suit to 1112345678999 and it splits into four sets and a pair, so all nine tiles 1 to 9 win:

Winning tileSplit
1111 + 123 + 456 + 789 + pair 99
2111 + pair 22 + 345 + 678 + 999
3pair 11 + 123 + 345 + 678 + 999
5111 + 234 + pair 55 + 678 + 999
9pair 11 + 123 + 456 + 789 + 999

4, 6, 7 and 8 split just as neatly — hence the 9-sided wait.

How Nine Gates is scored

A limit hand isn't added up item by item. The fan below are computed live by the same scoring code the game uses.

Nine gates (九子連環)Limit
Total10 fan · Limit

Anything over 10 fan scores 10 (the limit).

Fully concealed, waiting with 1112345678999 dots; someone discards 5 dots: Nine Gates, a limit hand.
Concealed hand (門前清)1
Self-drawn (自摸)1
Pure one suit (清一色)7
No flowers (無花)1
Total10 fan · Limit

Anything over 10 fan scores 10 (the limit).

The same suit, but the 1 dots were declared as a concealed kong: no longer Nine Gates — just concealed hand, self-draw, Pure One Suit and No Flowers, which still adds up to the limit.
SituationFan
Nine GatesLimit
One suit but not 1112345678999 (Pure One Suit)7 fan
Pure One Suit + concealed hand + self-draw9 fan

How it relates to other hands

Nine Gates odds

How many tiles of one suit in the opening hand

Nine Gates needs all 14 tiles from one suit. A 13-tile opening hand has 9 or more of one suit only 0.25% of the time, and 10 or more 0.028%.

Most tiles of one suit in the opening handChance
5+ tiles65%
6+ tiles27%
7+ tiles7.8%
8+ tiles1.6%
9+ tiles0.25%
10+ tiles0.028%

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

Fourteen random tiles that are already Nine Gates

Counting combinations exactly: 14 random tiles from the 136 (flowers excluded) form 1112345678999 of one suit plus one more of that suit with probability 0.0000000002% — about once in 490,000,000,000, rarer still than Thirteen Orphans at once in 3,200,000,000. In play you draw and discard, but you still have to reach that exact shape without claiming a single tile.

How often it happens in play

In 100,000 hands of computer play on this site, Nine Gates came up 0 times; Pure One Suit, in the same games, was 0.83% of wins.

When Nine Gates can happen

Nobody plans Nine Gates from the deal. It usually appears when a concealed Pure One Suit is nearly done and the shape happens to fit:

To practise concealed one-suit hands, open a table of online Hong Kong mahjong — the computers play with you.

Nine Gates in other mahjong styles

The same shape is a big hand in Japanese, Taiwanese and Chinese Official (Guobiao) mahjong, but the name, the score and whether the waiting shape matters vary: Japanese mahjong yaku list, Taiwanese mahjong tai table, Guobiao fan table.

FAQ

How many fan is Nine Gates?

In Hong Kong mahjong Nine Gates is a limit hand: Limit, the 10-fan cap, with nothing else added.

Can Nine Gates include a concealed kong?

No. This site requires no declared sets at all; even a concealed kong turns it back into an ordinary Pure One Suit.

Does Nine Gates have to be self-drawn?

Not on this site — winning on a discard counts the same. Some tables require a self-draw, so ask before you play.

Try it at the table

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