Well my first comment would be that you are going to need a fairly large sample on someone for that stat to be worth anything. Like you might play 25% hands preflop, then you have to play hands against that villain and then you have to actually make it to the river versus that villain where he can take an action versus you being the bettor. So just be careful that you aren't looking at it thinking that because you have something like 1K hands that somehow this stat is reliable cuz you might only have 1 or 2 occurrences on the river where you bet and he either folds, calls, or raises. So like if he folded 1 out of 2 times that means nothing. The other challenge is you don't know to what sizings he folded. A bunch of them could be hands where you had the nuts and overbet jammed the river which is going to get more folds, but you can't see that in that stat.


When I used to use a HUD I didn't have any river stats. Unless you can get at least 5K hands maybe even more on a villain I am not sure river stats will be that valuable.

Now to your question: It is just bluff odds, which is risk/risk+reward. Risk=your bet, reward=the pot. I found the easiest way to calculate these auto profit numbers for fold% is to assign the reward or pot the value of 1. Then assign the risk or your bet what ever fraction of the pot you are betting in a decimal

If you make a 1/2 pot bet on the river:
.5/1+.5=33% So if villain is folding more than 33% to a 1/2 pot bet then you are in autoprofit.

If you make a 3/4 pot bet on the river
.75/1+.75= 43%

If you make a pot size bet on the river
1/1+1=50%

So you get the idea and I think you had it already

This is where Minimum Defenses Frequency(MDF) comes from as well. 1-bluff odds=MDF which is the percentage of villains range that they have to defend to not be exploitable. So versus a 1/2 pot bet they need to defend ~67% or their range that arrived at that street, in basic terms. There is more to it than that, but it is a start