Effective Stack Sizes

Effective Stack Sizes

Poker Fundamentals
Mathematics of Poker

Effective stack size simply refers to the amount of money held by the player who has the smallest stack when considering a hand between two players. Why consider this at all? Read on to find out.

When given something simple, one should revel in its simplicity - and that's exactly what we're going to do during this mini, but mighty discussion on effective stack sizes. As far as poker theory and strategy goes, this may very well be the most straight-forward concept you'll ever encounter. Effective stack size simply refers to the amount of money held by the player who has the smallest stack when considering a hand between two players. 

Yep. That's it.

Effective Stack Sizes and Multiple Players

We’ve established that effective stack size is only a consideration for two players at a time, but this isn’t to say that more players can’t be in the pot. 

Here’s what I mean:

Player 1 has $200
Player 2: $50
Player 3: $100
Player 4: $150

The effective stack size between Player 1 and 2 would be $50; between Player 4 and Player 1, $150; between Player 3 and Player 2, $50, and so on. What you are trying to convey is how you stack up in relation to another player, so there can actually be multiple effective stack sizes in multi-handed pots. 

The Importance of Effective Stack Sizes

OK, so your mind probably isn't blown here - nor should it be - but the simplicity of the concept doesn't mean that considering effective stack sizes is useless. Let's say you are playing $100NL and you have $100, but your opponent only has a $60 stack. The effective stack sizes would therefore be $60 since, for the purposes of this hand, you might as well only have $60 too. After all, you can't force your opponent to front more money than they have in front of them. 

For this reason, effective stack sizes only apply to situations with two players. Not three. Not four. Not five – just two. This isn’t to say that there can’t be more players in the pot, only that the effective stack size applies to the smallest stack size between two players.

Effective Stack Sizes and Bet Sizing

The size of your stack and your opponent’s stack helps you work out your bet sizing; more specifically:

  • Implied odds - because small stack sizes won't see you getting paid off as well if you are chasing a draw)
  • Stack-to-pot ratios - because strategic thinking about effective stacks as compared to the pot size help make the best decisions
  • Fold equity - because small stacks aren't as scary as towering stacks, so if you have a meager stash, your opponent is less likely to fold

So, when you’re thinking about effective stack sizes, it’s good to remember that your stack size is really only as big as your opponent’s. You can’t squeeze more out of them than they have to give, and fancy strategies and bluffs are usually wasted effort when they can’t reap the rewards they were designed to produce. As always, when you’re playing poker, you want to be playing in response to your environment; this includes the who, the when the how and the HOW much.