Basic odds: outs and the rule of 2 and 4
3 min read · Updated 2026-09-26
You don’t need to be good at maths to use odds at the table. Three steps cover almost every decision with a drawing hand: count outs, estimate your chance, compare it with the price.
Step 1: count your outs
Outs are the unseen cards that turn your hand into the likely winner.
Flush draw:
A♥ 10♥· Board:K♥ 7♥ 2♣13 hearts in the deck, 4 already visible: 9 outs.
| Draw | Outs |
|---|---|
| Flush draw (four to a flush) | 9 |
| Open-ended straight draw (e.g. 8-9-10-J) | 8 |
| Two overcards (e.g. A-K on a low board) | 6 |
| Gutshot straight draw (e.g. 8-9-J-Q, needs a 10) | 4 |
| Pocket pair hoping for three of a kind | 2 |
| Flush draw + open-ended straight draw | 15 |
Watch out — Don’t count outs that help someone else more: If the board is paired, your flush card could give an opponent a full house. Overcard outs are often shaky too. When in doubt, count fewer outs.
Step 2: the rule of 2 and 4
- On the flop, with two cards to come (you’ll see both turn and river): outs × 4 ≈ your chance in %.
- On the turn, with one card to come: outs × 2 ≈ your chance in %.
- Only use × 4 if you will really see both cards — if you face a big bet on the turn too, use × 2 on each street.
Exact figures assume your outs are among the 47 unseen cards on the flop (46 on the turn).
| Outs | Flop → river (exact) | Rule of 4 | Turn → river (exact) | Rule of 2 |
|---|---|---|---|---|
| 2 | 8.4% | 8% | 4.3% | 4% |
| 4 | 16.5% | 16% | 8.7% | 8% |
| 6 | 24.1% | 24% | 13.0% | 12% |
| 8 | 31.5% | 32% | 17.4% | 16% |
| 9 | 35.0% | 36% | 19.6% | 18% |
| 12 | 45.0% | 48% | 26.1% | 24% |
| 15 | 54.1% | 60% | 32.6% | 30% |
Tip — Big draws: take off a little: Above about 8 outs, the rule of 4 runs high. A quick fix: outs × 4, then subtract (outs − 8). For 15 outs: 60 − 7 = 53%.
Step 3: compare with the pot odds
Pot odds tell you how often you need to win for a call to pay off: divide the call by the total pot after you call.
| Step | Example |
|---|---|
| Pot before the bet | 100 |
| Opponent bets | 50 |
| You need to call | 50 |
| Pot after your call | 100 + 50 + 50 = 200 |
| You need to win at least | 50 ÷ 200 = 25% |
On the turn with a flush draw, you have about 18–20%. That’s less than 25%, so calling this bet loses chips in the long run — unless you expect to win extra when you hit. With the same draw on the flop and no more bets to come, 35% beats 25%: call.
Note — Handy bet sizes: Facing a half-pot bet you need 25%. A two-thirds-pot bet: 29%. A pot-sized bet: 33%.