What is a good big blind defense range vs an open?
The GTO solver Big Blind defense range at 100bb re-raises 14.7%, calls 29.4%, and folds 55.9% of hands in the fixed spot below.
This chart shows the big blind model facing a 2.5bb button open after the small blind folds. Only the button and big blind remain, so a call leads to a heads-up pot. The posted blind reduces the additional cost to call, but the big blind will be out of position. The displayed calls, raises, and folds describe the selected opponent model in this fixed spot.
The GTO solver chart is our CFR solver's 100bb ranges, with 2.5bb opens (3bb from the small blind). The other charts are the ranges Poker Shark's Arena opponents play, not recommendations for your own play. The Arena's GTO opponent is GTO-style: hand-written rules, a little tighter than a solver. The other types are modeled on real players. Percentages are how often each one takes each action.
Green is raise, blue is limp or call, and gray is fold. Each share fills that percentage of the cell. Raise includes all-in actions. The Arena charts specify no raise size. Use the hand lookup for exact percentages. These fixed snapshots do not expose a rake setting.
6-max, 100bb starting stacks, 0.5/1bb blinds. BB faces a 2.5bb open from BTN, with no callers. UTG, HJ, CO, SB folded. Only the opener and big blind remain.
Quick tip: This is defense against a button open, not a multiway pot. Different open sizes, opener ranges, or callers can change the decision.
Big Blind defending range by the numbers
Fixed reference figures, independent of the chart selected above. First-in comparisons count raises only; defense comparisons count raises plus calls.
For comparison, the GTO solver Small Blind defense range continues 15.3% of hands at 100bb, 28.8 points tighter than this seat. Figures count combos: pairs weigh six, suited hands four, and offsuit hands twelve. The opener can differ between defense seats; check each chart’s context.
Now play the spots, not just the chart.
Practice against opponents whose ranges are too loose, too tight, or too passive, and exploit the gap.
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