This is easy and very simple. Flat out, if you have four parts of a flush, you will make it 35% of the time. Odds are 1.86 to 1 against it, with 2 cards to come. With only the river to come, you will only make it 19% of the time. The odds are 4.11 to 1 against it.
Now, lets use something that can help you figure this all out on the fly. It's called the rule of two: multiply your number of outs by 2, then add 2 to get your odds of hitting it.
You have four parts of a flush. 13 cards of that suit, you have 4; that leaves 9 cards, or outs, that can help you.
Multiply by 2 and you get 18. Now add 2 to that. You get 20. Thats 5 to 1
(4:1) that you will make your flush. (20 goes into 100 five times). So it is 5-1
(4:1 or 1/5) that you will make it, period, and you will 35% of the time on the turn, 19% of the time by the river.
Now, same thing applies to straights, but here is where you are going wrong. Gap or no gap is the wrong way to look at it; use your outs! So, here are some figures:
You have an open end straight draw, then you have 8 outs to make your st8 (4 bottom of the st8 cards and 4 top of the st8 cards). You will make that 31.5% of the time by the turn (it's 2.17 - 1 against you) and 17.4% of the time by the river if you miss your turn card needed (4.75-1).
Now, using the rule of two, you see that it is 8x2+2=12. 12 will go into 100 a little more than 8 times. So, you are looking at 8-1
(7:1 or 1/8) hand odds that you will make it.
If you only need one card to make that st8, it is pretty dismal. That is only 4 outs. so, 4x2+2=10. You are looking at 10-1
(9:1 or 1/10) hand odds that you will make it. However, you often have more outs than that.
You hold: 5h6h
Flop: 6d7h9h
Lets count those outs with that hand and that flop;
2 6's for trips or quads
3 5's for two pair
3 8's (no heart) for a st8
1 8h for a flush/st8 flush
8 other hearts for a flush
___
17 outs. 17x2+2=36, so 2.77-1
(1:1.77 or 1/2.77) hand odds (100 / 36 = 2.77)
Now that you know the rule of two, use this chart to help out with the % chance of making it....
Please keep in mind, this is not pot odds. Typically you want your pot odds to be
greater than your hand odds, or it is not worth a flat call. In the example I gave you (2.7-1 rounded)
(should have been 1.7:1 making the rest of this paragraph sketchy) you would need that or better (3-1)
(2-1) to justify calling. If you are not getting that, you might want to raise the bet in order to get there. If the pot is 50.00 and you are looking at a flop bet of 50, that means you have to call 50 to win 100. That is only 2-1. That could mean fold
or raise, but that is
another lesson entirely. I am pointing out to you now only how to calc hand odds and use with odds of making it overall to compare and learn.
Hope it helps.
