Next steps · Poker strategy
Backdoor Draws in Poker: Runner-Runner Equity
By Pokerscope · Updated · 3 min read
Backdoor draws need two cards to improve, so each adds only a small amount of equity. A hand with several ways to improve can still have a meaningful chance to win.
In this guide
Multiple backdoors: 6♥5♥ against queens
You need both remaining cards to improve enough to win.
You hold 6♥ 5♥ against Q♦ Q♠ on K♠ 7♥ 2♣. No single turn card gives you a better hand than queens. A six or five makes only a smaller pair, and one heart does not complete a flush.
Yet your hand has about 10% equity. Across two cards, several things can happen:
- Two hearts make a flush.
- An eight and nine make a straight; other suitable rank pairs can also complete one.
- A six and five make two pair.
- Two sixes or two fives make three of a kind.
Some runouts still lose if queens improve. The useful point is that “no immediate outs” does not mean “no chance of winning.”
Backdoor flush draws
There are three visible hearts across your hand and the flop, so you need a heart on both remaining streets.
When only your hole cards and the flop are known, ten hearts remain among 47 unseen cards. After a heart turn, nine remain among 46 cards:
Backdoor flush completion ≈ (10 ÷ 47) × (9 ÷ 46) = 4.16%
This is the basis for the roughly 4% shortcut. With the two non-heart queens exposed in our example, the denominator changes to 45 and then 44, giving about 4.55% flush completion. Completion is not necessarily a win: a runout containing Q♥ can also improve the opponent.
Connected and disconnected backdoor straights
With the ranks 7-6-5, several pairs of ranks complete a straight:
- Three and four.
- Four and eight.
- Eight and nine.
When those cards are all available and the opponent’s cards are unknown, the combined completion chance is about 4.4%.
A more disconnected pattern such as 7-5-3 needs specifically a four and six. That completes about 1.5% of the time under the same assumptions.
Both are backdoor straight draws, but the connected pattern has more ways to get there. Count the useful rank pairs rather than giving every backdoor draw the same value.
Backdoor two pair and trips
With two unpaired hole cards such as 6-5, three sixes and three fives remain if none are otherwise visible. Catching one of each gives nine possible turn-river combinations, roughly 1% of runouts.
Catching two sixes gives three combinations, roughly 0.3%. Catching two fives gives another roughly 0.3%. Those are separate ways to make trips with either hole-card rank.
These are completion estimates. Some overlap with straights or flushes, and some still lose to the opponent’s final hand. Use a full equity calculation to account for all the outcomes together.
What does the extra equity change?
A few percentage points can matter when a decision is close. But about 10% equity is still a large underdog: it does not justify calling any price.
Compare the hand’s equity with the required equity, and consider whether the call gets you both remaining cards. The advanced drill helps build estimates for hands where several small sources of equity add up.
For direct draws that need only one helpful card, use the rule of four and two. Backdoors require two helpful cards, so that shortcut does not apply in the same way.