Rule of 2 and 4
A quick way to turn outs into a chance: outs times 4 with two cards to come, times 2 with one.
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- What it means
- A mental shortcut for the chance of hitting a draw by the river, close enough to use at the table.
- How it is calculated
- On the flop, with the turn and river to come, multiply your outs by 4. On the turn, with one card left, multiply by 2. The answer is a percentage.
- Worked example
- A flush draw has 9 outs: 9 × 4 = 36% on the flop against the exact 35.0%, and 9 × 2 = 18% on the turn against the exact 19.6%.
- Why it matters
- It runs high with many outs (15 outs gives 60% against the exact 54.1%), so use the exact figure when a decision is close.
Try it: Outs calculator, Printable cheat sheet
See also: Outs and the rule of 2 and 4, Pot odds, Required equity