Bet into a flush/straight draw?

I have been checking these around or seeing only small raises but I see a lot of people will bet these out on the flop thereby raising the pot if they hit. My quandary is that these hit infrequently. 16% for a gutshot straight and around 33% for OESD or flush.

So let’s see…(assume OESD or flush)
Assume your avg bet (before fold) is 3X BB.
Lets further assume that you will loose a small percentage of the ones you hit….10%
So you loose 3XBB 70% of the time and say 15XBB 3% of the time (times you hit but loose).
But you win at least 15XBB every time you hit and win which is 27%.

15*.27 - (3*.7 + 15*.15) == 4.05 – (2.1 + 2.25) == 4.05 – 4.35 == -.3 or about break even.

So one needs to either bet less to see if they hit (unlikely) or win more when they hit to make it worth it. Are my logic and my calculations sound here?

The money in the pot has very little to do with this question. What matters, is whether your bet is for value or not. If you are drawing and have a 1/3 chance of winning, you should bet if you expect 3 or more people to call. Say you have the nut flush draw and get 2 of your suit on the flop. If you bet and 3 people call, you win 3 bets 1/3 of the time. You will lose 1 bet 2/3 of the time. So on average, for every 3 times you make this play you will win 3 bets once and lose 1 bet twice for a net of 1 bet positive. With a nut flush draw, you will win without the flush about as often as you will lose to a boat, so the boat isn't a critical factor in the calculation.

If only 2 people will call your bet, its a break even proposition if your odds are 1/3. Betting will only increase your variance but might be a good idea if your opponents pay attention to pot odds and it increases the chances they will pay you off if you do hit.

To value bet draws on the Turn, you need twice the return on investment because your odds are roughly half what they were on the river. You need 6 people to call your bet. That's not going to happen, so don't do it.

Another thing to consider is the semi-bluff value of your bet. If there is a good chance you will win the pot by betting, you get some value for your bet from that. At low limit limit hold'em, this usually doesn't work.

Oh I get it. OK, thanks again.

Originally Posted by Xanadu

To value bet draws on the Turn, you need twice the return on investment because your odds are roughly half what they were on the flop. You need 6 people to call your bet. That's not going to happen, so don't do it.

Assuming my bolded correction is correct. I think you are saying that if I haven't hit my flush/straight by now then there is little sense betting for value on the turn and I should look to fold to any raise.

The correction is correct

You usually shouldn't fold. You just shouldn't bet. Here is where the size of the pot really does matter. You have about a 1/6 chance of drawing now that the turn has come. A little better if it is a flush draw. If, when it comes to you, you should call a bet if there are 5 bets to win (the pot plus prior bets this round). You have to add up what's in the pot and compare it to what you have to pay to see the next card. If it's less than 5 times, you should generally fold, greater, then call.

There are other factors which play into this decision. If there are players after you to act after you call, and you expect them to call and not raise, you can call a little more often as you have better odds if these people call. At some tables no one ever raises and it is easy to make this decision. If you call and the bet is raised, it is always correct to call again, as your odds are better for this call than the last one. If you have to call 2 or 3 bets, do the math. Often when you have to call 2 bets, you may likely have to call 3 because the original raiser may cap, so take that into consideration. The other factor is implied odds ... you may not quite have the pot odds for a call on the turn, but you know you can get another bet or 2 out of the river if you hit ... the probable value of this implied winnings should be added to the pot when making your decision.