The same hand, 8♠7♠, is worth almost nothing 15 big blinds deep and can win you a huge pot 150 big blinds deep. The difference is not the hand. It is stack depth.
Stack depth decides how many streets you still have to play, whether a later card can rescue you, and how much one wrong decision costs. Outside of preflop ranges, it is the single biggest influence on how a hand should be played.
- ✓What matters is the effective stack — the smaller of the two stacks — not how much you have.
- ✓SPR = effective stack ÷ current pot. That number decides whether you can ever fold a made hand postflop.
- ✓Below 20 big blinds the game collapses into push or fold, and postflop barely exists.
- ✓20 to 50 big blinds is the easiest range to misplay, because a 3-bet leaves you committed to the pot.
- ✓Implied odds only exist when stacks are deep. Small pairs and suited connectors live entirely on them.
Look at the effective stack, not your own
This is the step most players skip, and it is the most basic one.
You have 200 big blinds; your opponent has 30. The real depth of this hand is 30 big blinds, not 200. Your opponent can only ever lose 30, so the other 170 will not move in this hand. If you are holding suited connectors thinking “deep stacks let me see a cheap flop”, you are making decisions based on a depth that does not exist.
The reverse is just as true. If you have 25 big blinds at a table full of 200 big blind stacks, every hand you play is a short stack hand. Money on the table that is not in front of you changes nothing.
In multiway pots, work it out against each opponent separately. You have 100, player A has 40 and player B has 180. Against A this is a 40 big blind hand; against B it is a 100 big blind hand.
SPR: the number that decides how you play postflop
Stack depth is a preflop concept. The moment the flop lands, the number that matters is SPR, the stack-to-pot ratio:
SPR = effective stack on the flop ÷ current pot
Two situations show how much it matters. Both start 100 big blinds deep:
| Situation | Flop pot | Stack behind | SPR |
|---|---|---|---|
| CO opens to 2.5, BTN calls | 6.5 | 97.5 | about 15 |
| You open 2.5, opponent 3-bets to 10, you call | 21.5 | 90 | about 4 |
Same 100 big blind starting stacks. One extra preflop raise, and the room you have to work with postflop shrinks by almost four times.
SPR answers one question: is this hand worth committing your whole stack to?
- SPR below 3: top pair with a good kicker is usually enough to commit. There is not much to think about.
- SPR between 3 and 6: top pair is still playable, but three streets of heavy betting should worry you.
- SPR above 10: top pair is a medium hand. Committing a full stack normally needs two pair or better.
Below 20 big blinds: push or fold, and almost no postflop
Short stack play is not about being more aggressive. It is about ending the decision earlier.
Under 10 big blinds, preflop has two options: shove or fold. If you open-raise, you leave yourself less than half your stack behind, so any postflop bet is effectively all in anyway. You may as well do it in one move and collect the full fold equity while you are at it.
Between 10 and 20 big blinds there is more room, and open-raising still works, but decide one thing first: what is your plan when you get 3-bet? If the answer is “fold”, the hand should not have been raised.
Hand selection changes too. Small pairs and suited connectors are valuable at depth because they occasionally flop huge and win an entire stack. At 12 big blinds that prize does not exist, so their value drops sharply. High cards that hold up inside a calling range — something like A♥J♦ — go up in value instead.
20 to 50 big blinds: the easiest range to misplay
This is the depth old advice most often ignores, and the one where money quietly leaks.
The problem is the SPR after a 3-bet. Say the effective stack is 40 big blinds:
- You open to 2.5, your opponent 3-bets to 8, you call
- The flop pot is about 17.5, with 32 behind
- SPR is about 1.8
Which means that as soon as the flop is dealt, almost any made hand you have is already committed. There is no “call and see the turn” option, and no room to bluff.
So at this depth, the right frame of mind for a 3-bet is this: deciding to 3-bet is deciding whether you are willing to get all the chips in. If you are not, do not 3-bet — call or fold instead. Using a 3-bet as preflop pressure without being ready to commit is the most expensive mistake in this range.
100 big blinds and up: implied odds and multi-street planning
Deep stacks are valuable because there is still a lot of money left to win, and that brings a group of hands back to life that were useless when short.
Implied odds are the core of deep play. Hold 5♦5♠ against a preflop raise and your immediate pot odds are almost never enough — you flop a set about 11.8% of the time, roughly 7.5 to 1. For the call to be worth it, you need to expect to win more than seven times the call amount after you hit.
- Effective stack 100 big blinds, calling 3: there are 97 behind to win after you hit. Worth it.
- Effective stack 20 big blinds, calling 3: there are at most 17 left to win. Not worth it.
The practical shortcut: calling a preflop raise with a small pair should cost no more than 5% of the effective stack.
The second feature of deep play is that position is worth more. A high SPR means the flop, turn and river are all still to come, and you act after your opponent on every one of them. That informational edge compounds. The deeper the stacks, the bigger the gap between the button and the small blind. For how position shapes what you can do, see preflop basics.
The third is that bluffs need a plan. A deep-stacked bluff is rarely “scare him off this street”. It is deciding on the flop what the turn and river bets will be, so the whole line looks like a real hand. Improvised single-street bluffs are easiest to catch when stacks are deep.
Cash games and tournaments handle depth differently
Being short means two completely different things in the two formats.
In cash games you choose your depth. Lose chips and you can top back up to 100 big blinds whenever you like, so most of your time is spent deep, building postflop skill. Buying in short is a strategic choice, not something forced on you.
In tournaments the clock chooses for you. Blinds rise on a schedule, so even if you never lose a hand your depth slides from 100 big blinds down to 20, then 10, and you cannot reload. Tournament players have to be fluent across the whole spectrum, and short stack play most of all — every tournament ends up there.
Two more factors are tournament-only. Antes make every pot bigger, which raises the reward for stealing and widens the range a short stack should shove. The payout structure means a chip is not worth its face value: close to the money, busting costs more than the chip count suggests.
