SB 20bb 3-Bet Jam

Context

The SB 20bb 3-Bet Jam is a common tournament play, particularly in the middle to late stages when stack sizes are shallow. The small blind (SB) has about 20 big blinds (bb) and faces an open-raise, typically from a late-position player (e.g., button or cutoff). Instead of calling or making a smaller 3-bet, the SB moves all-in. This play leverages fold equity and simplifies decision-making.

Why 20bb?

At 20bb, the SB is in a stack-depth range where many hands become difficult to play post-flop if calling. A standard 3-bet might commit too much of the stack, leaving awkward post-flop stacks. Jamming eliminates positional disadvantage and forces the opponent to make a decision for their tournament life. It also maximizes fold equity against wide opening ranges. The 20bb threshold is not strict; similar principles apply from about 15-25bb.

Implementation

Key factors for choosing this play:

• Opponent's opening range: If the opponent opens wide (e.g., from the button), the SB can jam with a polarized range: strong value hands (e.g., TT+, AJ+) and some bluffs (e.g., A2s, K9s) that have equity against calling ranges.
• Fold equity: The SB needs the opponent to fold often enough to make the jam profitable. At typical tournament ICM pressures, opponents should fold many hands like KQ, A8s, or 99 if they believe the SB's range is strong.
• Stack sizes of other players: If the big blind (BB) has a large stack or is active, the SB may adjust ranges to avoid being squeezed.

Risks and Considerations

• Massive risk: Jamming 20bb is a high-variance play; losing means a significant stack reduction or elimination.
• Opponent adaptation: If the opponent traps with premium hands, the SB can lose a large pot. However, most players at shallow stacks open wide rather than trap.
• ICM implications: Near the bubble or in satellite tournaments, avoiding elimination may outweigh chip accumulation. The SB must consider tournament equity.

In practice, the SB 20bb 3-Bet Jam is a staple of push/fold charts and is often recommended for aggressive players who want to apply pressure. It is less common in cash games due to deeper stacks and no ICM pressure.

Summary

The SB 20bb 3-Bet Jam is a tactical all-in re-raise from the small blind when holding about 20 big blinds against a late-position open. It capitalizes on fold equity and simplifies post-flop play, but carries high risk and should be adjusted based on opponent tendencies and tournament stage.