Turn sizes, overbets and checking back

In this lesson

• Overbet when you hold the nut advantage and the opponent's range is capped.
• Choose overbet bluffs that block the calling hands and leave the folding hands alone.
• Check medium hands to keep the pot under control.
• Match the turn size to the shape of your betting range.

Read first: Betting the turn again · Advice, not a lock: every lesson opens.

Concepts used: Nut advantage, Bet sizing and polarisation, SPR and commitment

The size that gets the stacks in

Size has a job: to get the right amount of money in by the river. With 9.1 bb in the pot and 95.7 bb behind, as in the last lesson, how big must two equal bets be to get everything in by the river? Each called bet of f times the pot makes the pot 1 + 2f times bigger, so two of them need (1 + 2f)² = 1 + 2 × 95.7 / 9.1. That is about 1.85 times the pot on each street.

So in a single-raised pot at 100 bb, three-quarter-pot bets do not get the stacks in by the river. Only overbets do. A range that wants to play for stacks — the nuts and the bluffs that go with them — needs big sizes; a range of medium hands does not want stacks in at all.

When an overbet fits

An overbet asks a lot of the other player and gives a lot of odds to nobody: it works when your range holds hands theirs cannot, so their bluff-catchers face the nuts and must fold or pay. That happens when their range is capped, after they checked or called small on earlier streets, and the card or the line left you with the strongest hands.

Rail's river solve has a size above the pot, and it shows the pattern: in position after a check it overbets noticeably more often than out of position as the first to act, and the hands it overbets are the very strongest and the bluffs, not the medium ones.

Pick overbet bluffs the same way: hands that hold cards of the other player's best calls, and none of the cards their folding hands need.

Medium hands check

The other side of a polarised turn is the check. Middle pairs and weak top pairs gain little from a big bet: better hands call it, worse ones fold. In Rail's turn solves they are among the classes that check most, which keeps the pot small and their showdown value alive.

Rail's turn tree has one bet size, three quarters of the pot, plus all-in when the stacks are short, so turn overbets are taught here with the arithmetic and with the river solve, which has a 150% size. The river split below is graded with that size as its own group.

Rules of thumb

• Size for the stacks: count how big the bets must be to get them in by the river.
• Overbet when the other range is capped and yours holds the nuts.
• Overbet bluffs hold cards of the hands that would call.
• Medium hands check, keeping the pot small.

When they break

• Against a player who never folds a pair, overbet only for value.
• With stacks already short, the overbet is just the all-in: there is no size left to choose.

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.