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How To: Analyze Calling An All-in
Introduction
A dozen or more times a week there are hands posted in this forum that are asking if Hero should call an all-in. I don't even have to scroll half-way down the first page of BC to see all of these threads that have a hand like this in them:
AKo vs relatively unknown player - Poker Forums
jj with king on the board 2nl - Poker Forums
a few hands 2nl - Poker Forums
Line check with AKs ($10NL) - Poker Forums
a few hands, first night of my op- 2nl - Poker Forums
2 QQ 6-max hands for review - Poker Forums
None of these hands were given with analysis. Instead, they're just dumped on the forums like "Hey guys which button do I mash here?" Deciding whether or not to call an all-in is pretty easy, so I'm going to show you guys how to put on your big girl panties and analyze your own hands a bit.
Required Software
Go here and download PokerStove if you don't already have it. PokerStove does equity calculations for us based on ranges against ranges so that we don't have to do them by hand. If you want to learn the keyboard shortcuts and whatnot to do complicated stuff in PokerStove, watch this 4-5 minute video that might be NSFW for language (link).
The Process
There is a pot size, you are facing a bet size, and you have an equity against your opponent's range. These are the three things that affect the EV of calling an all-in. The pot size and bet size are given to you, and you can use PokerStove or your own calculations to determine your equity. This creates a process that I'm going to overly exaggerate here into four steps for easy consumption:
Step 1: Identify the size of the pot. This is the size of the pot after your opponent has bet, including all of the money in the pot before your opponent bet and the amount he bet that you're allowed to call.
Step 2: Identify the size of the bet. This is how much you're calling.
Step 3: Determine your equity by one of the previously mentioned methods (using PokerStove or others).
Step 4: Figure the fraction bet size/(bet size + pot size). If your equity is larger than this, then a call is +EV. If your equity is lower than this, then a call is -EV. If your equity is exactly this, then a call has the same EV as a fold.
An Example
On the turn there is $8.50 in the pot and my opponent (who I have covered) shoves another $11.50. The board is AsThTc3s and I hold Td4d. I think my opponent's range (for the sake of this example) is {AA, 33, AK+, Tx}. Can I make a profitable call?
Step 1: What is the pot? There was $8.50 in the pot, and our opponent has bet another $11.50 that we can call, so the pot is $20.
Step 2: What is the bet? We are calling $11.50, so that's the bet size.
Step 3: What is our equity? Here's a quick screenshot of PokerStove:
So our equity is 39.394% against this range.
Step 4: The fraction bet/(bet+pot) is 11.5/(11.5+20), which is 36.5%. This is less than our equity of 39.394%, so it's a +EV call.
Where To Go From Here
Once you get this and regularly use it (both at the table with estimations and away from the table in your study and hand analysis) then you'll realize the only variable that changes is the range you put your opponent on. This is why estimating ranges is so important, so practice!
So from now on if someone posts a hand where they were facing an all-in, and they haven't shown the range they've put their opponent on, you should link them to this post and suggest they do their own analysis first.
Extra Credit: Finding The Exact EV
Like I mentioned earlier, when we're facing an all-in there are three factors that affect our EV: the size of the pot, the size of the bet we're calling, and our equity. While the shortcut I offered above (which I'll prove in a minute) will tell you if calling an all-in is +EV, sometimes it can be useful to know the exact EV of a call against a certain range. I'm going to quickly illustrate how to do this here.
There are two possible cases after we call. In the first case, we win the hand and win the amount of the pot. In the second case, we lose the hand and lose the amount we called. Our equity will tell us how often we'll pick up the full pot and how often we'll lose our bet as follows:
EV = (our equity)(pot size) - (our opponents equities)(bet size)
Keep in mind that our equity plus our opponents' equities will always equal 100%. So let's look at an example. Suppose that heads up after our opponent goes all-in for $4 the pot is $10 and we have 18% equity against his range. What is the EV of a call?
Our equity: 18% (or 0.18)
His equity: 100% - 18% = 82% (or 0.82)
Bet size: $4
Pot size: $10
EV = (0.18)(10) - (0.82)(4)
EV = 1.8 - 3.28
EV = -$1.48
So on average, this call will cost us $1.48.
Extra Credit: Proving The Shortcut
I said earlier that when our equity is greater than bet/(bet+pot) that the call will be +EV, when our equity is lesser than bet/(bet+pot) that the call will be -EV, and when our equity is equal to bet/(bet+pot) that the call will be 0 EV. Here I'm going to quickly prove that and show you where this comes from. Remember our equation from above?
EV = (our equity)(pot size) - (our opponents equities)(bet size)
Well let's call our pot size P, our bet size B, and our equity E for the sake of simplicity. This means our opponent's equity is (1-E) since our equity plus our opponent's equity has to add up to 100% (or 1). This gives us the following equation which we'll do a little algebra on:
EV = EP - (1-E)(B)
Now suppose a call is +EV. This would mean that
0 < EP - B + EB
B < EP + EB
B < E(P+B)
B/(P+B) < E
Which shows that our equity will be greater than bet/(bet+pot). Similarly we can show that the rest of this shortcut is correct.
Now go forth and do math.
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