The Value of Chasing a Flush
On occasions, you may find yourself going into a flop holding suited cards to see two of the three cards subsequently drawn belonging to the same suit. Whereas an inexperienced player might assume that the odds of getting the final card to complete the flush are “evens” (Two cards to be drawn, each one having a 3/1 chance of being a specific suit) this would be incorrect, and may lead to inadvertently betting against the odds when believing that they are in your favor.
The way to calculate odds in this instance, is to disregard any cards other than the two that you hold in your hand and the three (or more) that you can see on the table. In the event of having the first four cards of a flush after the flop, this is the way that the odds are reckoned:-
You have to accept that you can see only 5 cards from a total of 52, so there are 47 unseen cards. You also know that there are 4 cards of your suit already distributed, so that leaves a further 9 available. Therefore, the odds of seeing a card of your required suit drawn on the turn are 9/47 or 19%. If your suit does not come out on the turn, you then have a 9 (cards remaining that will complete the flush) divided by 46 (cards left in the pack) or 20%. Combine the two percentages (19% + 20%) and you will see that the odds of completing the flush are 39%, or slightly less than 6/4 in bookmakers terms.
You may have other outs available to you which may determine the way you choose to proceed. You can call or bet depending on whether the flop has presented you with a good pair or the possibility of a straight and, depending on position and the dynamics of the table you may wish to push forward to maximise the pot. Two things that you need to consider are whether your flush can be beaten by somebody holding a better prime card than yourself (especially if your suit is drawn on both the turn and the river), and whether there is a “slow player” on the table, already in possession of two pairs, trips or a straight who is just waiting for you to make a bet.
In conclusion, there are no hard and fast rules which determine whether you should or should not bet heavily solely on the basis of the opportunity to acquire a flush. However, it is essential to be aware of the odds of the final card you require being drawn, so that you can ascertain correctly the value of chasing a flush.