Odds of Making a Flush Draw on the Flop
Flopping a Flush is most unlikely and requires us to have two suited cards in the hole already. However, Flush draws are a lot more common, so it’s worthwhile knowing the odds of flopping four of the five cards required to make a Flush.
Odds of flopping a two card Flush draw with any starting hand – 2.58%
Odds of flopping a Flush draw with two suited cards – 10.9%
Odds of flopping a one card nut Flush draw with any starting hand – 0.17%
Odds of flopping a one card nut Flush draw with an Ax holding – 1.12%
Odds of flopping any one card Flush draw with an unsuited starting hand – 2.24%
The most useful piece of information here is that we will flop a Flush draw around 11% of the time when starting out with a suited hand.
While the probability of flopping a one card Flush draw with an unsuited starting hand is always 2.24%, it’s worth remembering that non-nut one-card Flush draws are not especially valuable holdings.
For the most part, we prefer our one card Flush draws to be to the nuts.
Odds of Making a Flush on the Later Streets
Let’s assume that we have flopped a Flush draw. How likely are we to make a Flush on the later streets?
Odds of making a Flush on the turn or river
When holding a Flush draw, there are always 9 cards remaining in the deck that can complete our Flush draw.
Odds of completing a Flush draw on the turn – 9/47 = 0.1915 or roughly 19.2%
Odds of completing a Flush draw on the river – 9/46 = 0.1957 or roughly 19.6%
Odds of making a Flush by the river
Here we will use the simple trick of calculating the probability of not hitting our Flush draw and then subtracting from 100%.
Probability of not hitting a Flush draw on the turn – 38/47
Probability of not hitting a Flush draw on the river – 37/46
Probability of not hitting by the river is 38/47 * 37/46 = 0.6503 or roughly 65%
Therefore the odds of making a Flush by the river is (100% - 65%) roughly 35%.
Implied Odds Analysis of a Flush
The implied odds of a Flush depend on two main factors.
Two-Card or One-Card – Two-card Flushes (made with both hole cards) always carry better implied odds than one-card Flushes. A two-card Flush on non-paired board texture is always strong enough to play for 100bb stacks with. Non-nut one card Flushes, on the other hand, are little more than bluff-catchers in many situations.
Paired or Unpaired Board – Flushes always carry the best implied odds on unpaired board textures. When the board is paired, Flushes need to be treated with more caution since our opponent may have already made a Full House.