What is Ippatsu? Conditions and When It's Cancelled Explained for Beginners

What is Ippatsu?

Ippatsu (一発) is a luck-based yaku in mahjong worth 1 han that completes when you win within one turn after declaring riichi. Called “ippatsu” meaning “one shot,” it has strong luck elements but occurs surprisingly often, making it an important yaku that enhances riichi’s appeal.

It should be learned together with riichi - riichi + ippatsu + tsumo gives 3 han, and with uradora on top, it can quickly become a high-scoring hand.

Detailed Explanation of Ippatsu

Conditions for Ippatsu

To complete ippatsu, you must meet these conditions:

Counting One Turn

One turn means: From when you declare riichi until it’s your turn to draw again

You (Riichi) → Right → Across → Left → You (This is 1 turn)

When Ippatsu Is Cancelled

These actions cancel ippatsu:

Usage Examples

Real Game Situations

Example 1: Hoping During Riichi

"Riichi! Ippatsu please!"
"If I get ippatsu, it's mangan"

Example 2: Reaction to Calling

"Ugh, they ponned. Ippatsu gone"
"Kan cancelled it, rinshan ippatsu-canceller"

Example 3: Celebrating Success

"Rii-ichi (riichi + ippatsu) came!"
"Ippatsu ura-3 for haneman!"

Ippatsu Probability and Expected Value

Ippatsu Probability

Wait Shape and Ippatsu Rate

Related Terms

• Riichi: Prerequisite for ippatsu
• Tsumo: Self-draw win
• Ron: Win on opponent’s discard
• Uradora: Bonus after riichi
• Menzen: Closed hand state

Common Mistakes and Points to Note

Points Beginners Often Mistake

1. Doesn’t Work Without Riichi

   • Winning immediately from damaten isn’t ippatsu
   • Riichi is required

2. Calling Cancels It

   • You can’t call after riichi anyway
   • Other players’ calls cancel ippatsu

3. Even Ankan Cancels

   • Anyone’s ankan cancels ippatsu
   • All kan types cancel ippatsu

4. Second Turn Isn’t Ippatsu

   • Your second draw = no ippatsu
   • Understand the exact definition of 1 turn

Strategy for Aiming at Ippatsu

Riichi Timing

1. Early riichi

   • Other players call less
   • Higher ippatsu chance

2. Riichi with good shape

   • Easy to win shape
   • Ippatsu rate increases

3. Chase riichi also has ippatsu

   • Even after opponent’s riichi
   • 1 turn from your riichi

Strategy to Cancel Ippatsu

Defensive perspective:

• Intentionally call to cancel ippatsu
• Reduce opponent’s scoring
• Especially effective against parent riichi

Ippatsu and Other Yaku

Always Combined Yaku

Commonly Combined Yaku

Ippatsu Value

Basic patterns:

• Riichi only → 1 han
• Riichi + ippatsu → 2 han (doubled)
• Riichi + ippatsu + tsumo → 3 han (quadrupled)

Practical Considerations

Playing with Ippatsu Awareness

1. Riichi decision

   • Include ippatsu in expected value calculation
   • Earlier turns are more favorable

2. Watch other players

   • Be wary of riichi player’s ippatsu
   • Secure safe tiles

3. Calling decisions

   • Value of ippatsu cancellation
   • Balance with your own hand

Psychological Aspects

• Pressure: Fear of ippatsu distorts play
• Anticipation: Riichi player hopes for ippatsu
• Mind games: Timing of ippatsu cancellation

Conclusion

Ippatsu is a luck-based yaku, but it’s also one of mahjong’s exciting elements. It’s a limited yaku valid only within 1 turn after declaring riichi, but the joy when it completes is exceptional. Beginners should learn the two basics: “within 1 turn after riichi” and “cancelled by calls.” By considering expected value including ippatsu, you can make more strategic riichi decisions.