A Look at Backdoor-Flush Draws

A backdoor draw is one in which you need to hit a card on both the turn and river to improve your hand. For example, you hold the A 4 and the flop is Q 9 6. A club on the turn and the river would give you a flush. Backdoor draws are of little value by themselves, as you rarely are getting sufficient implied pot odds to draw solely on the merits of a backdoor draw; however, sometimes they add just enough value to your hand to draw when you have other outs, such as overcards or bottom pair and an overcard. I often hear people at the poker table say, "I had middle pair and a backdoor-flush draw." Backdoor-flush draws should rarely impact your strategy, yet I frequently hear players talking about them.



Let's first look at why backdoor draws by themselves are weak. To make a backdoor-flush draw, you first need to hit your suit on the turn, which is 10/47, and then hit it again on the river, which is 9/46. Multiplying these together produces .042, or 4.2 percent, which is about 23-to-1. Those aren't very good odds!



Also realize that backdoor draws require you to hit two cards, so you will often need to pay a bet on both the flop and the turn. Therefore, you need even better than 23-to-1 implied pot odds on the flop to justify calling when you include the cost of the turn bet.



Let's look at this in more detail:

• Assume you are in a $1-$2 limit game and are faced with a $1 bet on the flop, which will close the betting.



• To complete your draw, you will most likely need to call a turn bet, also, so it is important to look at your implied pot odds.



• Since you will sometimes be folding on the turn, we can estimate your average risk. You will continue your draw about 20 percent of the time on the turn (10/47). Therefore, your average total investment is $1 + (0.20 × $2) = $1.40 (the actual investment is slightly higher, since you face the possibility of a raise on the turn).



• To justify this investment, you need a pot of approximately 23 × $1.4, which is $32. You should call on the flop only if you expect to win at least $32 (assuming that you have no other draws).



You would need to be in a capped pot preflop with several opponents to even have a chance of getting close to a pot that big. These types of pots are extremely rare, and even when they do occur, you will need to be closing the betting or you will run the risk of a raise behind you, given all that action. Realize that whatever limit you are playing, you can use the 32-to-1 implied pot odds that we calculated above as the basis for the number of small bets you need to win to make a backdoor-flush draw. If you were playing $10-$20, you would need an expected pot of $320. In $20-$40, you would need an expected pot of $640, and so forth. The math is shown here to demonstrate that backdoor-flush draws have little merit unless you have some other draws to add to them.



There are times when a backdoor-flush draw can turn a fold into a call, but it is also important to realize that there are two different types of backdoor-flush draws, one of which is more valuable than the other:



1. You hold two cards of the same suit in your hand and one hits the flop. For example, you hold the A 10 with a flop of K 7 3.



2. You hold one suit in your hand and two of the same suit hit the flop. For example, you hold the A 10 with a flop of K 7 3.



Note how the first is more valuable than the second. In the first scenario, your flush is concealed if you happen to hit it. In many cases, you'll be able to get in a nice raise or reraise on the river.



There are several problems and risks with the second type of backdoor-flush draw, in which you hold only one card of the suit in your hand:



• The first problem is that there will be three cards of the same suit on the turn. If one of your opponents hits a flush, there could be some raising and/or reraising, making your draw to the river more expensive.



• If you do manage to hit your flush, there will be four cards of the same suit on the river. You are unlikely to get a lot of action unless you are up against a very weak opponent.



• Also realize that these types of draws have close to no value unless you are drawing to the nuts or close to it. I would place no value on a draw to the third-best flush when you hold only one card of the suit. Your draw is already 23-to-1 to complete, so you don't want to hit it and lose. For example, you hold the Q 10 and the flop comes 6 3 2. Your backdoor draw to the Q is quite weak, given that anyone holding the A or K would beat you. Compare this to the first type of backdoor-flush draw, in which an opponent would need two cards matching the same suit to beat you.



Most players consider backdoor draws too frequently in their decision-making process. Hopefully, this column has shown some of the drawbacks. Even in those cases in which you are trying to justify a call, note that you won't get a lot of value out of backdoor draws when you hold only one card of the backdoor-flush suit in your hand.

Matthew Hilger is the author of Internet Texas Hold'em. This column contains excerpts from his upcoming book, Texas Hold'em Odds and Probabilities: Limit, No-Limit, and Tournament Strategies. You can ask Matthew questions in his poker forum at http://www.internettexasholdem.com/.