Stack-to-pot ratio and commitment

In this lesson

• Work out the SPR on the flop from the pot and the stacks.
• Name the hands that play for stacks at a low SPR.
• Explain how dangerous boards and deeper stacks weaken one-pair hands.
• Compare how a 3-bet pot plays at 100bb and at 200bb.
• Avoid folding after most of your stack is already in.

Read first: Which hands bet and which check, Defending against a flop bet · Advice, not a lock: every lesson opens.

Concepts used: SPR and commitment, Bet sizing and polarisation

SPR sets how strong a hand must be

The stack-to-pot ratio on the flop is the effective stack divided by the pot. It tells you how many pot-sized steps are left before everything is in, and so how strong a hand must be before it is happy to get there.

• Button against big blind in a single-raised pot: 97.5 / 5.5, about 17.7.
• The big blind 3-bets the button to 10 bb and is called: 90 / 20.5, about 4.4.
• A 4-bet to 22 bb, called: 78 / 44.5, about 1.8.

At 17.7 one pair is a hand to control the pot with; at 4.4 a good top pair or an overpair is often happy to put it all in; at 1.8 almost any pair with a good kicker is.

How a flop bet commits you

In the 3-bet pot, a flop bet of a third of the pot is about 6.8 bb. Called, the pot is 20.5 + 6.8 + 6.8 = 34.1 bb with 83.2 bb behind: the SPR falls to about 2.4. One more pot-sized bet and a shove cover what is left.

So the first bet is a decision about the whole hand. Before you bet or call the flop at a low SPR, ask whether you will be happy to get the rest in on most turns. If not, check or fold now rather than paying twice.

Folding after you are committed

The costliest mistake at a low SPR is to put in a third of your stack and then fold for the rest at a good price. Rail flags it in your own hands. If the hand was worth putting that much in, it is usually worth the last bit; if it was not, the mistake was earlier.

Deeper stacks do the opposite: at 200bb the same 3-bet pot has an SPR around nine, and one pair is back to being a hand that controls the pot.

The flop drills come from Rail's flop library, at 6-max 100bb. Your own hands on flops it did not solve, or at other depths, are read from the nearest solved flop or by the heuristic.

Rules of thumb

• Work out the SPR on the flop before you bet or call.
• Low SPR: decide on the flop whether you will play for stacks.
• At an SPR around four, overpairs and good top pairs usually do.
• Do not fold for a small last bet after putting in most of your stack.

When they break

• Against a range that only shoves the nuts, even a committed-looking hand can fold.
• Deep stacks raise the SPR: one pair goes back to pot control.

Example hands

Practice

The lesson is mastered when every exercise below that Rail can grade is passed. Missed items come back later as review cards.