The all in concept was invented to prevent über-rich mobsters from running over small honest guys at the poker table.

Back in the bad old days

Before the all-in rule was invented, if you had $500 at the table and $10,000 in the bank, if an opponent bet $20,000 into the pot, you could not call him, even if you ran across the street and withdrew all your money from the bank. Even if you had the absolute nuts.

To avoid people betting their cars and farms and wives (or husbands) some humanist genius introduced a rule called "table stakes". It states that in a poker hand you can only bet whatever money and chips you had on the table when the hand started. You cannot reach for your wallet and get more money. You cannot go to the bank and mortgage your condo.

To handle the case where one player bets all his money and the opponent has less money at the table, the all in rules were introduced. We'll walk you through them.

Calling is always allowed

No matter how little you have in your stack, you can always call with the rest of your chips. When you call with all your remaining chips, you call all in.

Example

There's $200 in the pot. You have $50 left and your opponent bets $200. If you want to call, you call all in by placing your last $50 in the pot.

In this case, the opponent first gets $150 back, the amount you couldn't match. Then there is a showdown and the player who shows down the best hand picks up $300 - the $200 originally in the pot plus $50 from each of you.

So, you can always call, but you can only win as much from your opponent as your call legitimates.

More players = more complicated

All-in rules for two players are pretty straightforward, as we saw above. When three or more players are involved, it can get pretty messy. Especially if you're in a home game and have to balance a beer jug while doing the math.

The ruling principle is that each player matches as much of the opponents' bets as she has left in her stack.

First, the smallest stack matches all opponents' bets. These chips are put in the "main pot". Then the second smallest stack matches the remaining opponents' bets with whatever is left in his stack and creates a side pot. And so on.

Example

There are three players with stacks as follows:

Player A: $10

Player B: $50

Player C: $200

All players move all in. Let's start with the smallest stack and create the main pot. Player A has $10 and matches $10 each of the other players bets. A main pot of $30 is created. This is the money that player A can win.

Then remaining chips of player B are matched to the bet of player C. Player B has $40 left, so we take $40 from player C and make a side pot of $80.

When all matching is done, player C still has $150 left in his bet. This money is returned to player C immediately, and then the remaining cards are dealt and the showdown is performed.

The following pots are contested:

Main pot: $30: contested by A, B and C.

Side pot: $80: contested by B and C.

Now if player A has the best hand, he wins the $30 main pot. Then players B and C compare their hands to see who wins the $80 side pot.

If, on the other hand, player B or C has the best hand, this player wins both the main pot and the side pot.

Betting in All-In Situations

Typically, if a player goes all-in for less than half the amount of a full raise, his bet is considered to have no effect on the betting options. That is to say, if a player bets $100, and another player goes all-in for $125 and a third player calls, the original player could not now re-raise, as this would be in effect raising himself. The third player, on the other hand, could still raise instead of call, as he has not yet had the option to raise.

Exposing Cards During All-In Situations

Providing that there is not more than one player who still has more chips in his stack involved in the pot, there is no penalty for exposing cards once a player is all-in and called. In tournaments, in fact, it is mandatory. However exposing a card while a player is considering whether to call an all-in usually merits a penalty. In most card rooms, exposing cards to reduce or encourage action, especially in a tournament, is not allowed.

Rebuying

In a rebuy tournament, if you go all-in and lose all your chips, you can buy more chips if you are still within the prescribed rebuy period. If you do this, you must do so immediately. You cannot leave the table and come back. If you do not have the money on hand to rebuy, you are out of luck, unless you can borrow from someone else at the table, buy the chips, then go get money to repay him or her.

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