outs
MathAliases: outs, 牌张, 活牌
Outs are the remaining cards that complete your draw to the strongest hand. Out-counting + the 4/2 rule is the basic tool for estimating drawing equity.
Outs are the remaining cards that complete your draw to the strongest made hand. Counting outs is the foundation of equity estimation when drawing.
Detailed Explanation
Common draw out counts:
| Draw type | Outs | Example |
|---|---|---|
| Flush draw | 9 | 2 suited in hand + 2 suited on board |
| Open-ended straight | 8 | 87 on a 65X board (need a 4 or 9) |
| Gutshot | 4 | JT on a Q8X board (need a 9) |
| Flush + straight draw | 15 | AhKh on Qh Jh 8s |
| Set draw (with a pair) | 2 | Holding 88, hoping for an 8 set |
Rule of 4/2 (quick equity estimate)
- Rule of 4 (flop seeing both turn and river): equity ≈ outs × 4
- Rule of 2 (turn seeing the river): equity ≈ outs × 2
Example: flush draw 9 outs, calling on the flop assuming you go to the river → 9 × 4 = 36% equity.
More precisely (works well for small out counts):
- 9 outs true equity ≈ 35% (Rule of 4 says 36%, small error)
- 4 outs true equity ≈ 16.5% (Rule of 4 says 16%, accurate)
- 15 outs true equity ≈ 54.1% (Rule of 4 says 60%, overestimate)
Common mistakes when counting outs:
- Double-counting: 9 flush outs + 8 straight outs ≠ 17 — subtract 2 overlapping outs
- Ignoring opponent redraws: you draw to the nut flush, but the opponent has a set — they can redraw to a full house on turn / river
- Dead outs: an out that gives the opponent an even stronger hand (e.g. your straight-completing 8 also makes them a set)
Common Use Cases
- Drawing decisions: outs → equity → compare to pot odds
- Semi-bluff evaluation: part of a semi-bluff's EV comes from outs
- Training fast estimation: skilled players count outs + equity in 1-2 seconds
- Table shortcut: in-game you don't compute exactly — the 4/2 rule's approximation is enough