Outs and the rule of 2 and 4
Outs are the unseen cards that improve a drawing hand to a likely winner; count them to estimate equity.
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- What it means
- An out is a card still in the deck that would turn your hand into the best one. A flush draw has 9, an open-ended straight draw 8, and a gutshot 4. Outs that might still lose, such as pairing an overcard, are not clean and are worth less.
- How it is calculated
- Count the cards that complete the draw and take away any you can already see or have counted once. Then estimate equity: outs × 2 with one card to come, or outs × 4 with both the turn and river to come.
- Worked example
- A flush draw has 13 − 4 = 9 outs. With two cards to come, 9 × 4 ≈ 36%, close to the exact 35%. With 15 outs the rule says 60% but the exact figure is 54%: above about 8 outs the rule of 4 runs high.
- Why it matters
- Compare the equity with the price. A 9-out draw facing a pot-sized bet on the turn needs 33% but has about 20% with one card to come, so it must fold unless it can win more later.
Try it: Poker math, Pot odds calculator, Outs calculator, Printable cheat sheet
Formula and worked example: Outs and the rule of 2 and 4 in poker math
Lessons that teach it: Count the cards that complete your hand, The rule of two and four · lessons other than the free one need an invite
See also: Equity, Required equity, Pot odds, Draw