Can't remember how to calculate immediate fold equity for blind steals

2 scenarios

We min open SB to steal the BB, what fold % do we need BB to have to make it immediately +EV

I'm trying this so far

We invest 1.5 with the min open now the pot is 3 so we do

(bet size)/(pot+2xbet size) so that's (1.5)/(3+1.5+1.5) which is 1.5/4.5???

33%?


Scenario 2, SB limps and we want to iso raise with 72o and hope they fold

Sb limps, pot is now 2

BB Hero raises to 5 so we invest 4

So (bet size)/(pot+2xbet size) would be (4)/(2+4) = 4/6 = 66%???

Pls help

or is it 1.5/6 and 4/10? ugh

It sounds like you're trying to calculate your Break-Even%, AKA Alpha. Don't include your own investment as part of the reward.

BE% = Risk / (Risk + Current Pot)

Scenario 1:
risk = 1.5bb
reward = 1.5bb
BE% = 1.5/3 = 50%
So you need them to fold at least 50% of the time to break even on a pure bluff.

Scenario 2:
risk = 4bb
reward = 2bb
4/6 = 66.6%
So you need them to fold 2/3 of the time to break even with a pure bluff.

---
When in doubt, use an expected value equation. for a pure bluff:

EV = (fold% * change-in-bankroll) + (call% * change-in-bankroll)

Scenario 1:
EV = (fold% * +1.5) + (call% * -1.5)
EV >= 0 when fold% >= 50%

Scenario 2:
EV = (fold% * +2) + (call% * -4)
EV >= 0 when fold% >= 66.6%

damn, thanks =)