Draw odds

Backdoor flush draw: the runner-runner odds

Three cards of a suit on the flop. You need two more in a row. It almost never comes, but it is not nothing, and it is worth knowing exactly how much it is.

• 10spades left in the deck
• 21.3%a spade on the turn
• 4.2%spades on both cards

Work it out

Worth about one out

One out, with two cards to come, hits 4.3% of the time. A backdoor flush draw hits 4.2%. So when you add up your outs on the flop, a backdoor flush draw counts as about one more. A backdoor flush draw and a backdoor straight draw together are worth about two outs, and two outs hit 8.4%.

That is only true when you will see both cards. If he bets the turn and it is not a spade, the draw is dead. With one card to come, a backdoor draw is worth nothing.

Why it still matters

• It turns a close fold into a close call, one out at a time.
• When the turn is a spade, you have a real flush draw: nine outs and 19.6% on the river.
• With the ace of the suit, as here, no other flush can beat yours.

What it is not: a reason to call a big bet on its own. Ace-high with a backdoor flush draw is still ace-high.

Other draws

• Flush draw
• Open-ended straight draw
• Gutshot
• Two overcards
• Straight flush draw
• Double gutshot
• Set mining
• Try the quiz