Confusion with The 2x4x Rule
dukeroyal
Red Chipper Posts: 16 ✭✭
Let’s say I have a flush draw on the flop and the only way to beat the villain is by hitting my flush. With 2 cards left I have about 35% equity, correct?
So if the villain bets pot I have 33% pot odds (excuse me if my terms are incorrect) so it is a +EV call correct?
So if the above is true than my confusion lies in the fact that in order for me to realize that 35% equity do I not have to see both cards? Do I not really only have 18% equity? (9 outs * 2 (one card))
And would you not then need someone to bet 1/4 pot to even BE?
So confused. Thanks for your help?
So if the villain bets pot I have 33% pot odds (excuse me if my terms are incorrect) so it is a +EV call correct?
So if the above is true than my confusion lies in the fact that in order for me to realize that 35% equity do I not have to see both cards? Do I not really only have 18% equity? (9 outs * 2 (one card))
And would you not then need someone to bet 1/4 pot to even BE?
So confused. Thanks for your help?
Best Answers

LeChiffre NetherlandsRed Chipper Posts: 417 ✭✭✭Let’s say I have a flush draw on the flop and the only way to beat the villain is by hitting my flush. With 2 cards left I have about 35% equity, correct?
Roughly correct, yes. If villain has a set or two pair it's less, if you have pair outs it's more.
So if the villain bets pot I have 33% pot odds (excuse me if my terms are incorrect) so it is a +EV call correct?
Assuming the 35% equity, yes.
So if the above is true than my confusion lies in the fact that in order for me to realize that 35% equity do I not have to see both cards? Do I not really only have 18% equity? (9 outs * 2 (one card))
The 4x2x rule dictates that each out on the flop gives you 4% equity, whereas it gives 2% once you reach the turn. You have 9 outs, so 9*4% = 36% equity which is indeed roughly the 35%.
Just apply 4x on the flop and 2x on the turn and you're good. The 2x doesn't refer to the number of cards which still have to come (which I think is where your confusion lies), it's just the multiplier you use on the turn. 
ericmwhite Red Chipper Posts: 34 ✭✭That's right. Realizing ~35% equity in that situation means that you would have to see two more cards. So you would need to include subsequent rounds of betting when calculating odds. If you would fold to a turn bet if you miss your flush you have to reduce your equity to ~18%.
Also, you have to reduce your # of outs based on the cards that get you to a flush but improve V's hand enough to beat you.
One of my friends built a tool that might help you work through this: https://premiumpokertools.com/guidedanalyses/shouldyoucall. There's a bit at the end where he lays out pretty clearly how to think about future betting rounds when deciding whether or not to make a call . 
Red Red Chipper Posts: 1,842 ✭✭✭✭I'd add: you also have to take in account your eventual implied odds (how much is V paying you when you hit your flush?) as well as your next street(s) fold equity (can you steal the pot later?).

Sully Red Chipper Posts: 744 ✭✭✭IMO it's important to think 20% on the flop unless:
a)you have a plan to see both cards. Too many players call the flop thinking 38% and then fold the turn.
b) as @Red mentioned you take into account implied odds. However, especially in the case of flush draws, it's hard to get paid as they are very visible and even harder to get value if OOP

LeChiffre NetherlandsRed Chipper Posts: 417 ✭✭✭Because in the games I’m playing no one ever bets under half pot and playing a 2way pot that is only going to give me 25% pot odds which doesn’t give me the 18% I need to see one card? Am I wrong?
You're right. However:
That's where implied odds come in. Indeed you are not getting the right direct odds to pay for the turn card. If villain bets 50 into a pot of 100 on the flop, and you only have 20% equity, you need to make 5 times (100/20) your investment back in order to breakeven. Your investment is 50, so in order to break even you want the pot to at least grow to 250. Since the pot will be 200 after you call, getting another 50 in is usually not a problem. Villain might double/triple barrel, or you can bet small for value on the river if villain checks turn. So it's a slamdunk call on the flop.
Answers
Some have a hand "too strong to fold"
Some have a worst FD
So there is still room to get paid. How big is this room is the question
This story only applies if the flop bet is an allin by the way.
Poker Math That Matters
By Owen Gaines
Doug Hull's book is excellent even tho it's not really for math geeks  it's very accessible:
https://tinyurl.com/yctcab3k
I am definitely guilty of calling the flop bet and folding on the turn because my equity all of a sudden went from 35% to 18% haha!
So how are you playing your flush draws then? How much are you adding for implied odds?
Because in the games I’m playing no one ever bets under half pot and playing a 2way pot that is only going to give me 25% pot odds which doesn’t give me the 18% I need to see one card? Am I wrong?
Last question I think I have about this. Then if I call a flop bet with only 20% equity I need to win 5x my investment of 50. This makes sense.
But what changes then if I call another 1/2 pot bet on the turn? Is it the same math but just recalculated with your turn bet?
So to clarify my thinking :
Pot size on flop : 100
Villain 1/2 pot bet : 50
Hero : Call 50 with 20% equity so need to win 5x of investment or 250 to be +EV
Turn card : not the suit I’m chasing
Villain 1/2 pot bet : 125
Hero : calls 125 with 20% equity so I need 5x the investment or 625 to be +EV (which would be really hard to achieve)
But maybe I pick up some outs have 25% equity then only need to win 4x my investment which is 500 which is a lot more attainable because if hero calls the turn bet the pot is already 500!! Man if this is right I’m going to have to be careful because I’m going to convince myself to chase way too many draws now haha.
That's indeed how you should look at it but I'd like to add it's not really that hard to achieve if you're in position for that price. You will have the ability to bet for value when checked to (doesn't have to be large of course given the price you paid on the turn) when you hit or call or raise villain's river bet. I would say in position you can still call against most opponents for that price. Out of position it's much harder since you rely on villain not to check back, which is very likely when the flush hits and you check to him. Of course you could consider donk betting but let's leave that aside for now. The point stands.
Another factor should be how much you and villain have left behind. If that is already less than what your implied odds tell you he should still put in on later streets, you don't have the right implied odds!
If villain bet pot on the turn, it's of course going to be even harder to call. In that case you can decide to either fold or consider a semibluff raise (an option you also have even if he bet 1/2 pot)
Makes sense right? If villain requires you to have 25% equity to call the bet, and you have 25% equity, you don't need much implied odds cause you're breaking even on a call :)