This was a 1/2 game multi-way pot where I had odds to call preflop from the small blind.

The rainbow flop was checked around where I had an inside straight draw.

Turn gives me the nut straight with a second spade on the board. I check with the intent of check-raising. It's checked around to the button, who bets $7 into the $12 pot. I raise it to $21. It's folded around and the button calls. I gave her just under 3-1 odds to make the call.

Was my bet size a mistake on my part, or was her call the mistake?

Do you think that should depend on how much you lost on the river after she hit her flush and you check/called?

Her call was 'fine' but essentially break even at 3 to 1 unless she also considered that any of her over-cards might be good. We don't play poker to break even, but it's pretty hard to pass up the 'correct' calling odds after we put some chips in a pot.

Betting in multi-way pots can be tricky since you may not want to bet too small and entice a 2nd or 3rd caller to tag along once you get the first caller.

C/R sizing can be even trickier. We don't know your stack sizes so there will be less to offer you on the 'right or wrong' front. You also need to consider your opponent's image when you use a c/r. Certain opponents will not call unless they get the correct odds and you can use this 'against' them in both directions when you are ahead or behind (strong or weak).

Even if there was a 1-gap on the Board for your gutter you risk your opponent figuring out what you might have and thinning down their calling range, which means you may have to make the call more attractive to them. Thus offering +EV odds to call with a draw but 'better' odds to call with 1-pr and 2-pr hands that are crushed.

Being OOP here you are accomplishing two things with your c/r. One, you are charging any drawing hand 'your' price to continue. And two, you are getting your 'value' on the Turn that you may not get on the River if you 'all of a sudden' lead out.

Typically at 1-2 a player will call 'any' sized bet, but they pay way more attention to c/r sizing. So you really need to think about the correct sizing based on stacks, opponents as well as the 'true' odds an opponent may need to call. GL

Ok, let's say I assume she would bet $25 on the river if the flush card comes. Her implicit odds are 5.75 to 1 with me reraise of $21.

If I assume that she would put in a $50 raise, then her implicit odds are 7.4 to 1.

In those cases she is easily getting the right odds to call a flush draw. Do I have that right? My original raise of $21 was likely too small.

Thanks. How did you determine that 3-1 is break even for a flush draw when the flush draw odds are just over 4-1? Is it considered break even because of the implicit odds, or am I missing something else?

Yes. If you are losing (on average) an additional $25 on the river, she basically has to call $12 on the turn to win $12 (preflop)+$7 (her bet)+$21 (your bet)+$25 (your river call) = $65.

A 'clean' flush draw going to the River is basically 20% to hit, so if you 'charge' anything more than 4 to 1 then you are making a +EV bet and your opponent is making a -EV call ... UNLESS as you indicate that your opponent can count on you to call a River bet. That is counting the chickens before they hatch and is typically called 'implied' odds.

If she raises to $50 on the Turn, then she is putting in $43 (call $14 + raise of $29) to win $112, if you call. This is a 2 to 1 spot, hardly a payoff to hit a flush if you don't give her more chips on the River.

She would be offering you $29 to win $112 which is close to 3 to 1 and an easy call if you know she's on a flush draw ... and obviously an easy call with the nuts and probably an easy shove/raise spot for you.

You can only calculate 'implied' odds against chips that 'may' go into the pot later. You can discuss if she is creating enough fold equity with a raise to $50 to make it worth her while, but that's hardly ever the case.

As you suggest, if she can count on you for $25 on the River, her calling odds are now about 4.5 to 1 ($14 to win $79), which now makes it 'correct' to call .. and thus makes your bet too small if you 'know' that you will pay her off on the River. Her $25 River bet is not at risk because she only puts it in when she hits.

These 'maths' are real easy to calculate when we know both hole cards. Bet sizing needs to take into consideration the whole range an opponent may have and also their willingness to call even though they may be getting incorrect odds.

Most rec 1-2 players are more than willing to call a 3 to 1 bet with most of their range, not just flush draws .. if they even take the time to consider the odds. Most will see it as 'just' $14 and make the call. Your job (or concern) will always be to figure out how to maximize what they will call to continue.

Not knowing your table image, I can't really say how a c/r of 'only' $14 would look to me in this same spot. I look at both the math and player in most spots. GL

Thanks for the explanation. Gives me some things to think about and focus on.

Don't have a betsize just to give one specific hand bad odds to cal. You're also trying to get called by pair/2pair/sets or straight draws that are drawing dead. If you wanted to give a flush draw bad odds why not just shove in $200?

Also don't sweat it to pay off flushes for one bet if they happened to hit it. If you're going to check the river when a spade comes and you never check with a flush, a straight becomes your best hand you will have. If you check and then fold a straight people are going to see that you fold way too often on rivers that improve draws and are going to bluff a lot. As long as you don't bet and call a raise on the river with straights you should be fine.