Poker Odds & Probability
Good Texas Hold'em decisions come down to comparing two numbers: how often you'll win the hand, and what the pot is offering you to keep playing. This page explains equity, outs, the rule of 2 and 4, and pot odds — the core math the tool does for you — and lists the equity of the matchups every player should know.
Equity
Equity is your share of the pot if the hand were played to showdown many times from the current point. A hand with 60% equity wins (or chops its share of) the pot 60% of the time on average. It accounts for both outright wins and split pots, and the equities of all players in a hand always add up to 100%. This is exactly what the calculator reports for each seat.
Outs
An out is a card still in the deck that improves your hand to a likely winner. Counting outs is the foundation of drawing math:
| Draw | Outs | Why |
|---|---|---|
| Flush draw | 9 | 13 cards of a suit − 4 you can see |
| Open-ended straight draw | 8 | Two ranks complete the straight, 4 each |
| Gutshot (inside) straight draw | 4 | Only one rank fills the gap |
| Two overcards | 6 | Three of each rank left to pair |
| Flush draw + open-ended straight | 15 | A monster combo draw |
Be careful not to double-count cards that serve two draws at once, and discount outs that might make an opponent an even better hand.
The rule of 2 and 4
A quick way to turn outs into a percentage without a calculator:
- ×4 on the flop — with two cards still to come, multiply your outs by about 4 to estimate your chance of hitting by the river. A flush draw (9 outs) is roughly 9 × 4 = 36%.
- ×2 on the turn — with one card to come, multiply by about 2. That same flush draw is now 9 × 2 = 18% to hit on the river.
The ×4 step slightly overestimates when you have a lot of outs. For big draws (more than 8 outs on the flop), subtract roughly the number of outs above 8 — so 15 outs is closer to 15 × 4 − 7 ≈ 53%, not 60%. When you want the precise figure, that's what this calculator is for.
Pot odds
Pot odds compare the price of a call to the size of the pot. If there's $80 in the pot and a $20 call to you, you're risking $20 to win $100, so your break-even point is 20 ÷ (100 + 20)... more simply, the call costs you 20 ÷ 120 ≈ 17% of the final pot. Whenever your equity is higher than that break-even percentage, calling is profitable in the long run. Counting outs gives you the equity; pot odds give you the threshold; you compare the two.
Common pre-flop matchups
These are the classic head-to-head matchups every player should know. Figures are rounded and ignore small suit effects — use the calculator for exact numbers. The hand vs hand odds page breaks down each shape in more depth.
| Matchup | Type | Approx. equity |
|---|---|---|
| Pair vs. lower pair — e.g. A♠A♣ vs. K♠K♣ | Pair dominates | ~82% / 18% |
| Pair vs. two undercards — e.g. A♠A♣ vs. K♥Q♥ | Crushing | ~87% / 13% |
| Big pair vs. one overcard — e.g. K♠K♣ vs. A♠Q♦ | Pair favoured | ~70% / 30% |
| Pair vs. two overcards — e.g. Q♠Q♣ vs. A♠K♦ | "Coin flip" / race | ~54% / 46% |
| Domination — e.g. A♠K♣ vs. A♥Q♦ | Shared ace | ~70% / 25% (≈5% tie) |
| Suited connectors vs. two overcards — e.g. 7♥6♥ vs. A♠K♣ | Live underdog | ~41% / 59% |
How the calculator gets these numbers
Once the flop is dealt, the calculator usually enumerates every remaining board — it literally checks each possible turn and river, so the equity is exact. Before the flop the number of run-outs is enormous, so it switches to a Monte Carlo simulation: it deals a very large number of random boards and tallies the results, converging on the true equity to within a fraction of a percent. That's why a pre-flop number might shift by a hundredth of a percent between runs while a post-flop number never does.
A word on variance
Equity describes the long run, not the next hand. An 82% favourite still loses almost one time in five, and over a single session those losses bunch up in ways that feel absurdly lucky or cruel. Knowing the odds won't smooth the swings; it just makes sure the decisions you control are the profitable ones.