How to use it
- Choose whether you are on the flop or on the turn.
- Count your outs and enter the number.
- Enter the pot (including your opponent’s bet) and the amount you have to call.
- Call if your chance on the next card is higher than the equity needed, allowing for implied odds.
The formulas
- Next card: outs ÷ unseen, where unseen = 47 on the flop and 46 on the turn.
- By the river (from the flop): 1 − ((47 − outs) × (46 − outs)) ÷ (47 × 46).
- Rule of 4 and 2: outs × 4 on the flop, outs × 2 on the turn.
- Odds against: (unseen − outs) : outs.
- Pot odds: call ÷ (pot + call).
Worked example
A flush draw on the flop (9 outs), 100 in the pot and 20 to call:
- next card: 9 ÷ 47 = 19.1 %, odds 38 : 9 = 4.2 : 1;
- by the river: 1 − 38 × 37 ÷ 2,162 = 1 − 1,406 ÷ 2,162 = 35 %; the rule of 4 says 36 %;
- needed: 20 ÷ 120 = 16.7 %, so calling one card is profitable.
Common outs
| Draw | Outs | Flop to river | Next card |
|---|---|---|---|
| Gutshot straight | 4 | 16.5 % | 8.5 % |
| Open-ended straight | 8 | 31.5 % | 17 % |
| Flush | 9 | 35 % | 19.1 % |
| Flush and open-ended | 15 | 54.1 % | 31.9 % |