Poker outs: how to count them, the rule of 2 and 4, and when they are enough to call
Outs are the unseen cards that turn your hand into the winner. A flush draw on the flop has 9 outs: with one card to come you hit 19.6% of the time and with two, 35.0%. The rule of 2 and 4 gets you those numbers in seconds by multiplying your outs by 2 or by 4.
What outs are
An out is a card that, if it comes, gives you the best hand. If you hold on a flop, any 7 or any queen gives you a straight: 4 sevens + 4 queens = 8 outs. That is an open-ended straight draw; if only the sevens helped you, it would be a gutshot with 4 outs.
To count outs, always ask the same two questions:
- Which cards improve my hand? Count how many of each are left, removing the ones you can see on the board and in your hand.
- Does that improvement actually win? If the card gives you a straight but gives your opponent a flush, it is not an out.
The second question is what separates outs that count from outs that lose you big pots.
Clean outs and dirty outs
A clean out always gives you the best hand. A dirty out improves you but can also improve your opponent.
Example: you hold on and your opponent has a set of kings, . You see 9 hearts and think 9 outs. But the 4 of hearts pairs the board and gives your opponent a full house, and the ace does nothing for you against a set.
If the turn is the 8 of clubs (), of the 9 hearts the 4 and the 8 pair the board: you are left with 7 clean outs. Since we know their hand here, 44 cards remain: 7 / 44 = 15.9%, against the 19.6% (9 / 46) you would take for granted counting 9 outs.
The flop works the same way: against the set, your equity with two cards to come is 25.6%, not the 35.0% of 9 clean outs. Against ranges you do not know which outs are dirty, but you do know which cards are dangerous: board-pairing cards when your opponent can have a set, or flush cards when your straight is not suited.
Outs chart for the most common draws
| Draw | Outs | One card (turn to river) | Two cards (flop to river) | Rule of 2 / 4 |
|---|---|---|---|---|
| Pocket pair to set | 2 | 4.3% | 8.4% | 4% / 8% |
| Gutshot | 4 | 8.7% | 16.5% | 8% / 16% |
| Pair to two pair or trips | 5 | 10.9% | 20.4% | 10% / 20% |
| Two overcards | 6 | 13.0% | 24.1% | 12% / 24% |
| Open-ended straight draw | 8 | 17.4% | 31.5% | 16% / 32% |
| Flush draw | 9 | 19.6% | 35.0% | 18% / 36% |
| Flush draw + gutshot | 12 | 26.1% | 45.0% | 24% / 48% |
| Flush draw + open-ender | 15 | 32.6% | 54.1% | 30% / 60% |
The one-card column uses 46 unseen cards (turn to river). From flop to turn there are 47: with 9 outs, 9 / 47 = 19.1%. Overcards and pair-to-two-pair are the dirtiest outs on the chart: you often hit and still lose.
The probability with one and two cards
With one card to come the math is direct: outs / unseen cards. On the turn 46 cards remain (52 minus your 2 and the 4 on board): with 9 outs, 9 / 46 = 19.6%.
With two cards (flop to river, seeing both) it is easiest to calculate the chance of missing both and subtract it from 1:
P = 1 − (blank cards / 47) × (blank cards − 1) / 46
With 9 outs there are 38 blanks: 1 − (38 / 47) × (37 / 46) = 1 − 1406 / 2162 = 35.0%.
With 15 outs: 1 − (32 / 47) × (31 / 46) = 1 − 992 / 2162 = 54.1%. Notice that with 15 outs you are the favorite against a made hand if you see both cards.
The rule of 2 and 4
The rule of 2 and 4 gives you the number at the table without dividing:
- One card to come: outs × 2. With 9 outs, 18% (the real math gives 19.6%).
- Two cards to come: outs × 4. With 9 outs, 36% (the real math gives 35.0%).
The rule works very well up to 9 or 10 outs. With many outs the rule of 4 overshoots: with 15 outs it says 60% and the real math gives 54.1%. That 5.9-point gap can flip an all-in decision.
And the most important condition: the rule of 4 only applies if you will see both cards, meaning the money is all-in on the flop. If there is stack behind, your opponent can bet again on the turn and your price changes; in that case use the rule of 2 for the next card.
Outs and pot odds: when to call
Outs give you your equity; pot odds tell you how much you need. Required equity is what you pay divided by the final pot: A / (P + 2A).
Turn, flush draw. The pot is 30 bb and your opponent bets 15 bb. You need 15 / (30 + 30) = 25%. With 9 outs you have 19.6%: with no more money to win, it is a fold. For the call to be worth it you would need to win 16.67 bb more on the river when you hit: those are the implied odds you need.
Turn, flush draw + open-ender. Same pot and bet, but with 15 outs you have 32.6%: you call even if you win nothing more on the river. A combo draw like this can even raise.
The pot odds guide covers how to calculate the price; the key here is not to mix up one card with two: on the turn it is always one.
Common mistakes when counting outs
- Counting outs that give your opponent a better hand. A straight with three cards of one suit on board, or a flush on a paired board against a possible set.
- Counting the same card twice. With a flush draw + open-ender, the two straight cards of your flush suit are already among the 9 flush outs: it is 9 + 6 = 15, not 9 + 8 = 17.
- Using the rule of 4 with stack behind. If your opponent can bet the turn, you do not see two cards for the price of one.
- Trusting overcards. Against a better pair, a set or a draw, hitting your ace may not be enough.
How to practice it
Review the chart until the numbers for 4, 8, 9 and 15 outs come without thinking, then practice telling clean outs from dirty ones on real boards. In POKER AULA the Calculator counts your outs against a hand or a range and tells you which ones are dirty, and the Training mode puts you in drawing spots where you decide to call or fold, with the reasoning explained. Outs are taught from the Beginner course and combined with implied odds in the Medium level. You can try it free for 48 hours.
Frequently asked questions
How many outs does a flush draw have?
9: there are 13 cards of the suit and you already see 4 (2 in your hand and 2 on the board). With one card to come you hit 19.6% of the time and with two, 35.0%.
When do I use the rule of 4 and when the rule of 2?
The rule of 4 only if you will see the turn and river with no more betting, as in a flop all-in. In every other case use the rule of 2 for the next card.
What is a dirty out?
A card that improves you but can also give your opponent a better hand, like a heart that pairs the board when your opponent has a set.
Practice it with 48 free hours of all of POKER AULA
Level-by-level No-Limit Hold’em cash game courses, interactive Training with THE WHY behind every decision, a Calculator and Preflop Charts, in Spanish, English and Portuguese.