Maybe a dumb question but when a player overbets how do i calculate how much equity i need?

Lets say the pot otf is 100$ and my opponent donks allin for 250$. How much equity do i need here and how do i calculate it?

Thanks a lot in advance

41% of equity.


it's a simple calculation of pot odds

investment / pot + investment

pot= 100$

Villains bet allin for 250$

Current pot 350$

Hero should call 250$


350 : 250 pot odds simplified 7 : 5

5/(7+5) = 5 / 12 = 41% about

or 250/(350+250) = 250/600 = 41%

ok?

I also want to show you something interesting

The bigger our bet will be, the worse our chances become (we risk more to always win the same pot) because the chances are that our opponent will fold. At the same time the odds of our adversary will also become worse. Well, normal, no?

But no.

Because the way they get worse is not absolutely the same.
Example
P = pot
B = bet size

Breakeven bettor = B / (P + B)
Breakeven caller = B / (P + 2B)

Possible bets in texas holdem no limit in relation to the pot are tending towards infinity. Let's consider a huge episode, our chances that the fault works are getting closer and closer to 0 because we have to succeed almost 100% of the times to make breakeven.
From the point of view of those who call instead is not so bad because the call should never succeed 100% of the time but rather 1: 1 or equivalent to 1/2 or 50% this due to 2B. As a caller you always have the luxury of winning at least 50% of the time.

What do I want to say with this?
If we are the bettor a size too small to bluff may be wrong but at the same time a size too big to not entice our opponent to call can be even more wrong. We must be diligent in choosing the size. The opposing reading in this case is a fundamental thing if we can skim the range of our opponent until the river being able to assign a few combos of extreme value here that a bet pot or over bet could however be the right move.

I just do [cost of call]/[size of final pot after we call]

250/600 = 41.67%

Thanks a lot for the detailed responses. Im really bad in math lol

How do i calculate the equity i need when somebody 3b me preflop or goes allin?

Lets say i raise to 10 and i get 3b to 30. (20:60= i need 33,33% ?)

and what if i raise to 10, get 3b to 30, i 4b to 100 and villain jams 500 eff? (400:1000= i need 40% equity to call?)

Im sorry but im so bad at this

Assuming there were no other players (and blinds/antes etc) then those calculations are correct.
Just do [cost of call]/[final pot].

Since maths is hard, it can be easy to think of like this:
"I have to put 400 into a final pot of 1000, so - with this call - I'm contributing 40% of the pot. Therefore I need to win 40% of the time to break even."

It's the same calc used for river decisions when you're wondering if you should call. If villain makes a pot-sized bet of 100 into 100, then you need to call 100 into a final pot of 300. Ergo, your call needs to win 100/300 = 1/3 of the time to break even vs a pot-sized river bet.

If the 3-bet/4-bet wasn't all in, then it's not so clear cut, as you still have to play post-flop, but if the calculation comes out at 33.33%, then you can call the 3-bet if you think you'll win the pot a third of the time.

Aight thx man