Riichi Mahjong · Closed 1 / open 1
Chankan (Robbing a Kan) in Riichi Mahjong: Rules, Scoring and Odds
In riichi mahjong, Chankan (robbing a kan) is worth 1 han: when another player adds the fourth tile to a triplet they called with pon (an added kan, kakan) and that tile is your winning tile, you can take it and win by ron. It's 1 han open or closed and a yaku on its own.
On this page
The rules for Chankan
- Only an added kan can be robbed: the fourth tile added to an existing pon
- Not an open kan from a discard: that tile was a discard — if it was your winning tile, you could have ronned it then
- Not a closed kan: on this site, not even with kokushi musou. Tenhou and Mahjong Soul let kokushi rob a closed kan, so this is a difference
- As with any ron, it must be your winning tile and you can't be in furiten; passing on a chankan puts you in temporary furiten (permanent furiten if you're in riichi)
- 1 han open or closed, and a yaku on its own — no other yaku needed
How Chankan is scored
The yaku, han, fu and points below are computed live by the same scoring code the game uses.
Chankan · Ron
| Chankan | 1 han |
| Total | 1 han 40 fu · 1,300 points |
|---|
Non-dealer, East round, no dora, no honba.
Riichi · Chankan · Ron
| Riichi | 1 han |
| Chankan | 1 han |
| Pinfu | 1 han |
| Total | 3 han 30 fu · 3,900 points |
|---|
Non-dealer, East round, no dora, no honba.
Chankan is a ron, so fu are counted like any ron (10 fu for a closed ron); with a two-sided wait pinfu still applies.
How it relates to other yaku
- Ippatsu: an added kan only completes once nobody robs it, so a chankan within one turn of your riichi still keeps ippatsu.
- Rinshan kaihou: that's the kan caller's own replacement-tile tsumo; chankan takes the added tile away, so both can't happen together.
- Houtei: no one can kan once the wall is empty, so chankan never stacks with houtei or haitei.
- Double ron: if two players wait on the tile, both can rob it, following this site's double ron setting.
Chankan odds
Someone has to have called pon on your winning tile, draw the fourth one and choose to add it, so chankan is very rare. In 40,000 hands between four computers at normal level, chankan happened 0 times — far fewer than the 42 rinshan kaihou wins in the same games.
Chankan in other mahjong styles
Robbing an added kong is a shared rule across mahjong styles:
- Sichuan mahjong: 1 fan (Sichuan Robbing a Kong)
- Chinese Official (Guobiao), "Robbing the Kong": 8 fan (Guobiao fan list)
- Taiwanese mahjong: 1 tai (Taiwanese mahjong tai list)
- Hong Kong mahjong: 1 fan (Hong Kong mahjong fan list)
FAQ
How many han is Chankan?
Chankan is 1 han, and 1 han when open. It's a yaku on its own.
Can you rob a closed kan?
Not on this site — not even with kokushi musou. Tenhou and Mahjong Soul allow it for kokushi only; no other yaku can rob a closed kan under any common ruleset.
Can you rob an open kan made from a discard?
No. That tile was a discard, so a player waiting on it could ron it when it was thrown.
Does passing on a chankan put you in furiten?
Yes. Like passing on any winning tile, you're in furiten until your next discard, or for the rest of the hand if you're in riichi. To see it happen, play a few hands of free online riichi mahjong against the computers.
Related yaku
Rinshan kaihou Closed 1 / open 1
Houtei Closed 1 / open 1
Try it at the table
Riichi Mahjong — Play Japanese Riichi Mahjong free in your browser against three AI opponents. Standard online rules with red fives, ippatsu and ura dora, a yaku guide, wait and furiten hints, and three AI levels. No sign-up.