When a player is faced with a current bet amount that he has insufficient remaining stake to call and he wishes to call (he may of course fold without the need of special rules), he bets the remainder of his stake and declares himself all in. He may now hold onto his cards for the remainder of the deal as if he had called every bet, but he may not win any more money from any player above the amount of his bet.
- For example, let’s assume that the first player in a betting round opens for $20, and the next player to bet has only $5 remaining of his stake. He bets the $5, declaring himself all in, and holds onto his cards. The next player in turn still has the $20 bet facing him, and if he can cover it he must call $20 or fold. If he calls $20, thus ending the betting round, instead of collecting all bets into the central pot as usual, the following procedure is applied: since there is an all-in player with only $5 bet, his $5, and $5 from each of the other players, is collected into the central pot (now called the main pot), as if the final bet had been only $5. This main pot (which may include any antes or bets from previous rounds) is the most the all-in player is eligible to win. The remaining money from the still-active bettors, in this case $15 apiece, is collected into a side pot that only the players who contributed to it are eligible to win. If there are further betting rounds, all bets are placed into the side pot while the all-in player continues to hold his cards but does not participate in further betting. Upon the showdown, the players eligible for the side pot—and only those players—reveal their hands, and the winner among them takes the side pot, regardless of what the all-in player holds (indeed, before he even shows). After the side pot is awarded, the all-in player then shows his hand, and if it is superior to all others shown, he wins the main pot (otherwise he loses as usual).
There is a strategic advantage to being all in: a player cannot be bluffed, because he is entitled to hold his cards and see the showdown without risking any more money. Opponents who continue to bet after the player is all in can still bluff each other out of the side pot, which is also to the player’s advantage since bluffing between opponents may reduce his competition. But these advantages are offset by the disadvantage that the player cannot win any more money than what his stake can cover.