If you're in a 3 way and thinking of opening with an all in jam and you're assuming both players will fold 50% of the time what then would your total fold equity be?

EV = $won * win% - $loss * loss%

The only equation you ever need. In this case you have two ways of winning, either by getting two players to fold or getting called and have a showdown. It's not particularly useful to only calculate the fold equity in this case because it doesn't tell the full picture.

The whole fold equity would look like this:

Assuming pot = 1,5bb and you're playing vs SB and BB.

EV = 1,5 * (0,5 * 0,5) + 0,5 * (0,5 * 0,5) + 1 * (0,5 * 0,5) + .....

The first term is for when they both fold, this happens 25% of the time. The second one is just SB folding which also happens 25% of the time. The third is when only BB folds. After the dots the remaining 25% is when they both call so you have a showdown. In both cases of only SB or BB folding you need to add in the equity your cards have.

Three ways this is quite a complicated equation with lots of terms. For example I'll expand the term that calculates what happens when only SB folds:

EV = (0,5 * 0,5) * ( (0,5 + Stacks * 2 ) * equity - stack)

The SB gets added to the pot which you and BB share and divide it according to equity. The only term in the whole equation where fold equity is all you have is when they both fold.

0.5*0.5 = 0.25

But that's not even close to reality, as the person to your left will usually fold more often due to the active player to his left.

Tbh, I'm not really interested in calculating my fold equity. I'd just use a push chart, and maybe deviate from it slightly if I think the opponents are more cally/foldy than average.

As always thanks. You guys helped me see that it isn't just a simple matter of it being a black and white 25%