What is Kantsu (Quad)?
Kantsu (槓子) is a combination of 4 identical tiles in mahjong. While normal sets consist of 3 tiles, kantsu is a special form that uses 4 tiles but counts as 1 set.
The act of making kantsu is called “kan,” and when you kan, you draw a replacement tile from the dead wall (rinshan hai) and a new dora is revealed, causing significant changes in the game.
Detailed Explanation of Kantsu
Types of Kantsu
| Type | Explanation | How to Make |
|---|---|---|
| Ankan (Concealed Quad) | Quad collected by yourself | Kan with 4 tiles in hand |
| Minkan (Open Quad) | Quad using opponent’s tile | Add kan to triplet or daiminkan |
| Kakan (Added Quad) | Quad added to open triplet | Add 1 tile from hand to pon’d triplet |
Detailed Types of Kan
-
Ankan (Concealed Quad)
- Have 4 identical tiles in hand
- Maintains closed hand status
- Declare “Kan” and expose tiles face-down
-
Daiminkan (Big Open Quad)
- Hand pair + opponent’s discard
- Regular open quad
- Breaks closed hand
-
Kakan (Added Quad) / Shouminkan
- Add 1 tile to already pon’d triplet
- Risk of chankan (robbing the kan)
Kan Procedure
Basic Flow
-
Declare Kan
- Say “Kan” aloud
- Expose tiles according to type
-
Draw Rinshan Tile
- Draw 1 replacement tile from dead wall
- Hand maintains 13 tiles
-
Discard
- Discard 1 unwanted tile
- Game continues normally
-
Reveal New Dora
- New dora is added
- Called kandora
Usage Examples
Real Game Situations
Example 1: Ankan Decision
"I have 4 dora, let's ankan"
"Ankan a safe tile for rinshan kaihou chance"Example 2: Kakan Timing
"Got the 4th white dragon after my pon! Time to kakan"
"Late in the round, let's try adding kandora"Example 3: Tactical Judgment
"Opponent declared riichi, better avoid kan"
"Want to kan again for sankantsu"Advantages and Disadvantages of Kan
Advantages
| Advantage | Explanation |
|---|---|
| More Dora | Kandora may increase score |
| Rinshan Kaihou | Winning on replacement tile is 1 han |
| High Fu | Ankan 32 fu, minkan 16 fu |
| Hand Space | 4 tiles become 1 unit |
Disadvantages
| Disadvantage | Explanation |
|---|---|
| Opponents Get Dora | Kandora benefits everyone |
| Hand Becomes Fixed | Even ankan is exposed |
| Chankan Risk | Kakan can be stolen |
| Reduced Defense | Fewer tiles for defense |
Related Terms
- Mentsu: Tile combinations
- Koutsu: 3 identical tiles
- Rinshan Hai: Replacement tile after kan
- Chankan: Robbing the kan yaku
- Kandora: Dora revealed by kan
Common Mistakes and Points to Note
Points Beginners Often Mistake
-
4th Kan
- 4 kans in one round causes abortive draw
- Even with suukantsu, 4 kans by 3 players causes draw
-
Ankan After Riichi
- Sometimes cannot ankan after riichi
- Cannot ankan if wait would change
-
Dead Wall Depletion
- 14 tiles must remain in dead wall
- Sometimes cannot kan
-
Kantsu Set Count
- 4 tiles still count as 1 set
- Does not become 5 sets
Yaku Related to Kan
Yaku Involving Kan
| Yaku Name | Description | Value |
|---|---|---|
| Rinshan Kaihou | Win on replacement tile after kan | 1 han |
| Chankan | Win on opponent’s added kan tile | 1 han |
| Sankantsu | Make 3 quads | 2 han |
| Suukantsu | Make 4 quads (yakuman) | Yakuman |
Kan Tactics
When to Kan
-
Ankan Dora
- Guaranteed score increase
- Prevents opponents from using it
-
Ankan Safe Tiles
- Low risk
- Chance for rinshan kaihou
-
Aiming for Sankantsu
- Already have 2 kans
- Chance for high score
When to Avoid Kan
-
After Opponent’s Riichi
- Kandora increases deal-in risk
- Raises opponent’s score
-
Already Tenpai
- Risk of changing wait
- Faster to win as-is
-
When Leading in Points
- Avoid unnecessary risk
- Kandora could help opponents catch up
Conclusion
Kantsu is a special form using 4 tiles as 1 set, and kan brings significant changes to the game. While attractive elements like more dora and rinshan kaihou chance exist, there are also risks. Beginners should start with safe ankans and gradually develop judgment for kan timing. Kan is one of mahjong’s exciting features, but using it at the right moment is crucial.