It's impossible to make the correct decision at a poker table without knowing where you stand in the hand and where the hand can go.
Having the ability to read a board quickly and accurately is one of the key skills a poker player can learn.
Before you can read a board, though, you have to understand what outs, anti-outs, true outs and blockers are.
Anti-Outs, True Outs & Blockers in Omaha?
Outs: If you are behind in the hand, these are the cards you can hit to take a lead in the hand. For example, if you have a pair of jacks and your opponent has a pair of aces, you need to hit a jack to give you three of a kind.
This means you have two outs. (You hold two of the four jacks, leaving a total of two in the deck).
Anti-outs: An anti-out is a card that would have been an out to your hand, but that will strengthen your opponent's hand if you hit it.
For example, in the last example, say the player with the aces had hit three of a suit on the flop. If you hit a jack of that suit you have three of a kind, but your opponent has a flush. One of your outs is an anti-out.
True outs: True outs are the sum of your anti-outs subtracted from your outs. You have two outs, minus one anti-out, leaving you with one true out.
When a poker player talks about "outs" in a story, they're almost always referring to the true outs.
Blockers: A blocker is a card (or cards) you have in your hand that steals opponents' outs or creates anti-outs for your opponents.
For example, if you hold the 67, with a flop of 45K you have two of the flush outs, plus blockers to the straight flush. Any player with the nut flush draw cannot hit the 3 or the 8.
This gives you four blockers. Since an opponent cannot see your hand, they will almost always be unaware of your blockers.
This allows you to force your opponent into making mistakes in their pot odds calculations. With your two blockers, the odds of your opponent hitting his flush are 15% less.
It may seem excessive to be excited over an edge of 15%, but think about it this way: casinos make their money off table games where the casino has an edge of as little as 1%. Over one bet 15% is small; over thousands, it will add up to a fortune.
Your hand: 5 5 6 6 9 9 10 10
Situation: Obviously you have nothing, and have to hit to get a hand. This leaves you with outs and anti-outs. You can then subtract the anti-outs to get your true outs.
Outs: You have a double-wrap straight draw giving you 20 outs (5x3, 6x3, 9x3, 10x3, 4x4, Jx4).
Anti-outs: The better read you can get on what other players hold, the more accurately you'll be able to tally your anti-outs.
We'll assume you have no read, thus all anti-outs are valid. There are two flush draws out there. Of the like-suited cards left, you hold two in your hand, leaving 16 possibly in the deck.
(There are 13 cards of each suit. 13 - 2 (on the board) - 2 (they must have two in their hand to have the draw) - 1 (in your hand) = 8. Since there are two separate flush draws with the same variables, 8 x 2 = 16 outs to a flush.)
Of those 16, eight are anti-outs for you. For example, if you hit the 9, you have a straight, but you lose to the heart flush. Any cards that will give you a straight but give an opponent a flush as well must be counted as an anti-out.
You also have to count any nine as an anti-out in this situation. If a nine falls there will be 7-8-9 on the board. Out of all the straights you can make, this one puts you most at risk at losing to a higher straight.
Any player with J-T will have you beat. Since a hand with a J-T is likely to have been played, you have to count this as an anti-out.
Four nines in the deck. You hold the nine of diamonds, plus you counted the nine of spades and the nine of hearts in the flush anti-outs, leaving only the nine of clubs. This puts total anti-outs to nine.
True Outs: Your 20 outs minus the 9 anti-outs = 11 true outs.
Practice Question (Answers at bottom)
The Board: AK84
Your hand: QJJ8
Situation: It's your first hand at the table and you have no reads on any players. All players in the hand could be playing any four cards. You're assuming you will need the nuts to win.
This might seem like a lot of work, but the more you practice, the quicker it will become. Many beginner players only count their own outs, forcing themselves to make the mistake described in the blocker card definition.
The whole appeal of poker is having the ability to outplay your opponent to gain an odds advantage. Your goal is to get your money in when you have an edge. You won't always win, but long-term it will provide you with a healthy sum of money.
If you ignore anti-outs, as a result putting up even money with a -7% edge, you would be better off putting that money down on red for a single spin.
Answer to practice question: Outs=17, anti-outs=4, true outs=13, blockers=2.
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