Stack sizes also affect implied odds (i.e., how much you expect to win if you make a good hand based on the odds of hitting that hand). For example, suppose that you have small suited connectors (such as 6d7d). It is not a strong hand. There is a low likelihood of hitting a strong hand on the flop, such as a straight, flush or three of a kind. However, there is a very decent chance of drawing. To win a large pot, you will call bets on the flop, turn and river to hit a strong hand. If you hit that hand, you will want to bet a lot.

With a small stack size, you cannot expect to win a lot when chasing a draw. Playing on spec works best with a large stack because you can afford to chase those types of cards and make big bets when you hit them. When you have a small stack, you cannot afford to chase those types of hands nor can you bet large enough to win a large pot.

Stack Sizes
Small stack = up to 40 big blinds
Medium stack = 40-100 big blinds
Large stack = more than 100 big blinds

Buy-ins vary according to the location and type of poker game. Home games tend to have small stacks (i.e., $20 buy-ins where the blinds are $0.25/$0.50). Real-world casinos tend to allow small to medium stacks (i.e., $100 buy-ins with $1/$2 blinds), although large stacks are not uncommon (some do not cap buy-ins). Online poker rooms tend to allow players to have large stacks (i.e., 100 big blinds).

Large stack sizes have an influence on how players bet. Bluffing is more viable when players have more poker chips at their disposal. Players can take more chances, and can threaten other players with larger amounts of money in relation to the number of chips in the pot. Stack size also affects a player’s decisions based on how much he has left in his stack versus the size of the bet.

For example, if a player has an average top pair at the flop with $10 left in the stack, and you bet $10, he is more likely to call as he has most of his stack invested. However, if he has $100, he will be less likely to call since he will have to match any bets on the turn and river to see the end result. He is less likely to risk his larger stack with a weak hand.

Usually, the value a bluff increases with the size of a stack. However, average and marginal hands tend to lose value. For example, a top pair is not as likely to pay off when a large stack is involved (excluding bluffs and draws) because average hands will not pay off a large amount in comparison to the pot. Also, larger stacks mean fewer showdowns, and those showdowns tend to involve very strong hands (e.g., straights, flushes).