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Poker math glossary
The vocabulary of poker probability, defined precisely. Every term links to the tool or lesson where you can see it work.
- Equity
- Your share of the pot if the hand were played out every possible way from this point: the probability of winning plus your share of any ties. A hand with 35% equity in a $100 pot 'owns' $35 of it on average.
- Odds calculator
- Outs
- The unseen cards that improve your hand. A flush draw has nine outs; an open-ended straight draw eight; a gutshot four. Count them, then convert to a probability with the number of cards to come.
- Draw odds explorer Flush draw odds
- Clean out / dirty out
- A clean out improves you to the best hand and leaves the opponent few ways to overtake you. A dirty out improves you but also improves the opponent, or leaves them many redraws. The distinction only exists relative to a specific opposing hand or range.
- Draw odds explorer (advanced mode)
- Pot odds
- The ratio of what you can win to what you must risk: (pot + bet) : call. Facing $50 into $100, you get 3 : 1. Pot odds convert directly to the equity you need to call profitably.
- Pot odds calculator
- Break-even equity
- The equity at which calling and folding have the same expected value: call ÷ (pot + bet + call). A half-pot bet needs 25%; a pot-sized bet needs 33.3%.
- Pot odds calculator
- Implied odds
- Pot odds adjusted for money you expect to win on later streets if you hit. They justify calls that immediate pot odds do not — with the caveat that the future money is an estimate, not a fact.
- Implied odds calculator Implied odds module
- Reverse implied odds
- The mirror image: money you expect to lose on later streets when you hit but are still second-best — a weak flush against a bigger one, or bottom two pair against a set.
- Runout explorer
- Expected value (EV)
- The average result of a decision over many repetitions. EV of a call = equity × (pot + bet) − (1 − equity) × call. A positive-EV decision can lose on any single hand; over time it wins.
- Pot odds and EV
- Fold equity
- The part of a bet's value that comes from the opponent folding. A bet with no showdown equity breaks even when the opponent folds bet ÷ (pot + bet) of the time.
- Bluff break-even table
- Range
- The set of hands a player could hold, each with a weight. Equity is usually computed against a range rather than one hand because you never know the one hand.
- Starting hand matrix
- Combination (combo)
- One specific two-card holding. A pocket pair has 6 combos, a suited hand 4, an offsuit hand 12. Counting combos is how ranges are weighed and how blockers are valued.
- Starting hand explorer
- Blocker
- A card you hold that removes combinations from an opponent's range. Holding an ace halves the number of ways they can have pocket aces (from 6 combos to 3).
- Starting hand explorer
- Redraw
- A way for the player who is currently behind to get back ahead after you improve. A set has a redraw to a full house against a flush; that redraw is what makes some of the flush's outs dirty.
- Draw odds explorer
- Variance
- How widely results scatter around their expected value. Poker has high variance: a 70% favourite loses 30% of the time, and long losing runs are a mathematical certainty for winning players.
- Methodology
- Showdown
- The end of the hand, when remaining players reveal their cards and the best hand wins the pot.
- Odds calculator
- Nut draw
- A draw that, when it hits, makes the best possible hand of its kind — the ace-high flush draw is the nut flush draw.
- Flush draw odds
- Gutshot (inside straight draw)
- A straight draw missing one interior card: four outs, 16.5% by the river from the flop.
- Gutshot odds
- Open-ended straight draw
- Four consecutive cards that a card at either end completes: eight outs, 31.5% by the river from the flop.
- Open-ended straight draw odds
- Backdoor draw
- A draw that needs both the turn and the river — three to a flush or straight on the flop. A backdoor flush comes in about 4.2% of the time.
- Backdoor flush odds
- Rule of 2 and 4
- A table shortcut: multiply outs by 2 for the probability of hitting on the next card, or by 4 for two cards to come. Accurate to within a point or two up to about 12 outs, then it overshoots.
- Shortcut vs exact
- ICM (Independent Chip Model)
- A model that converts tournament chip stacks into prize-money equity: your chance of first is your chip share, and later places follow from the chips that remain. It explains why a chip won is worth less than a chip lost.
- ICM calculator Tournament math module
- Monte Carlo simulation
- Estimating a probability by dealing random run-outs many times and counting. Used when exact enumeration is impractical; always reported with the number of trials and its standard error on this site.
- Methodology
- Exact enumeration
- Computing a probability by evaluating every possible outcome. On the flop, that is all 990 turn-and-river combinations.
- Methodology