# Outs and Odds!

• Bronze
Joined: 12.03.2009
Hey there!

I have a question about outs and odds

For example, Imagine that I have an open ended straight draw after the flop is revealed: there are 8 cards that help me.

So, the deck has 52 cards. Two are in my hand, three are on the flop, so there are 47 cards remaining

The probability that one of those 8 cards comes is: 8 divided by 47 = 0,1702

But in the Outs and Odds chart of the bronze articles, the odds from flop to turn of an OESD is 5:1, i.e., 1/5 = 0,20

Same thing for Flush Draw: 9 outs in 47 cards -> 9/47 = 0,1914
In the chart, it comes 4:1, 1/4 = 0,25

what the hell??

• 7 replies
• Bronze
Joined: 14.11.2007
with a straight draw you say correctly there are 8 cards that help you to improve your hand and there are 47 cards in the deck. therefore your odds are 39 : 8, which is for practical reasons rounded to 40 :8 -> 5 : 1.
that means that in 1 out of 6 cases you hit one of your outs. that means that 5 :1 is not 1/5, but 1/6.
• Bronze
Joined: 12.03.2009
correct! one in six! so why 5:1 and not 6:1?

you mean that the 5:1 odds tell that we must lose five to win one? the left side number are the times we lose to achieve a single win?

EDIT: By the way, how can you really know that the 9 outs for the flush (or 8 outs for straight, wherever) are in the deck waiting to be dealt? There can be some outs that have been dealt, we don't know what cards opponents have...
• Bronze
Joined: 01.04.2009
Originally posted by MancaMulas
correct! one in six! so why 5:1 and not 6:1?
This was decided hundreds of years ago. It's not the sort of question you can answer with anything except because ...

Kind of like: Do you put your boot in the trunk or your trunk in the boot? I guess it depends which country you are in!
• Bronze
Joined: 14.11.2007
Originally posted by MancaMulas
correct! one in six! so why 5:1 and not 6:1?

you mean that the 5:1 odds tell that we must lose five to win one? the left side number are the times we lose to achieve a single win?
Basically that's right. In 6 games we will lose 5 times and win 1 time. That's what the odds tell you when they are 5 : 1

EDIT: By the way, how can you really know that the 9 outs for the flush (or 8 outs for straight, wherever) are in the deck waiting to be dealt? There can be some outs that have been dealt, we don't know what cards opponents have...
You cant really know it That's the point. Poker is a game with limited information. That's why you have to discount your outs when you are in a multiway pot. The more players are involved in a hand the more likely it is that you dont have your full outs.
• Bronze
Joined: 28.01.2009
the easiest way to calculate odds is to use the 2/4 rule...

aka if you have 8 outs = on the flop it is 8x4=32% and on the turn it is 8x2=16%

the difference is in +/- 1% and it's kinda the easiest way to get the percentages...
• Bronze
Joined: 08.06.2008
By the way, how can you really know that the 9 outs for the flush (or 8 outs for straight, wherever) are in the deck waiting to be dealt? There can be some outs that have been dealt, we don't know what cards opponents have...

"Wheter you use 45 or 47 unknown cards, the difference in the odds you obtain will be so small that it is unlikely to affect you play. But using the number 47 suggests a philosophical misunderstanding of poker and how to use mathematics to analyse it. Once your opponent looks at his hole cards and takes action, those cards are no longer unknown. As a matter of fact, once he looks at his cards and you sense anything at all, his cards cannot be considered random". Barry Greenstein
• Bronze
Joined: 03.07.2007
There are 2 math notations:
1. probability x/y (might be converted to %).
2. odds a:b

They are not equal!

For example:

2:1 odds

means that out of 3 tries: something will fail to happen 2 times and happens 1 time

equals

1/3 = 30% in probability notation

odds | probability
1:1 -> 1/2, 50%
2:1 -> 1/3, 33%
3:1 -> 1/4, 25%
4:1 -> 1/5, 20%