[Warik]

[ QUOTE ]

Try using this rule. To convert a:b to a probability, just take b/(a+b). EG 9:1 against is 1/(1 + 9) = 1/10 = .1. To go the other way, .0416 = 1/(a + 1) <=> .0416 a + .0416 = 1 <=> a = (1-.0416)/.0416 = 23. So a runner-runner flush is 23:1 against. (Note that 1/(23 + 1) = .0416)

On a poker note, you can't call a bet on the flop getting 23:1 if you have only a runner runner flush draw. That's (mostly) because you'll also have to pay a double size bet on 4th street to draw at your hand on the river. Sklansky went through this calculation in depth in one of his lesser read books (maybe PGL??) and determined that you need something like 28:1, I don't really remember. But backdoor draws can add value to a hand that has some to begin with, sometimes swinging a fold to a call. See TOP for a great discussion of this. A classic example in HE is overcards on the flop that also have a 3 flush and 3 straight. (Note that drawing at a flush/straight on 4th street will also allow you to often catch an winning pair you wouldn't have otherwise.)

[/ QUOTE ]

Thanks. I understand the conversions perfectly.

Makes sense about the runner-runner draws. To call a 50 cent bet on the flop I'd need $11.50 (23 x $0.50) or actually $14 (28 x $0.50 like you mentioned) in the pot. The highest I've ever seen post flop is about $5 in the loosest of games. We'd need quite a few maniacs in there to get the pot that high, and I don't think I'd like to need 2 cards to make my hand vs. multiple maniacs. [img]/images/graemlins/smile.gif[/img]

Now, does this conversion and odds determination hold true after the river card is seen and the board is analyzed?

Let's say, for example, I have KJo and flop is KJ6 rainbow. We go through the standard bet/raise/call procedure and see that the turn is an ace. I get to the river and see another ace.

So, I have two pair, aces and kings, but any ace beats me, so do two jacks and two kings... but pokercalc.com says I have an 80% chance of winning.

So...

.80 = 1/(a+1)
.80a + .8 = 1

.80 a = .2

a = .25

That's .25:1... so as long as there's a quarter in the pot it's OK to call a raise? That doesn't make sense given the board.


or worse... if I have Q3 clubs and the board has 4 hearts and a Q, pokercalc says I'm 29.15% to win.

.2915 = 1 / (a + 1)

.2915a + .2915 = 1
a = .7085 / .2915
a = 2.43

There will always be at least $2.43 in the pot on the river... but obviously it's a mistake to call here.

I take it these calculations are only good when determining if I should wait out my draw but are of no significant meaning when it comes down to the end?