PREFLOP CHART · ~13% 3-bet · ~3% call
SB 3-bet range vs BTN open — 100bb cash
From the small blind, facing a BTN open at 100bb, GTO solvers heavily prefer 3-betting to flatting. The SB is sandwiched between the BTN raiser (still left to act) and the BB (also still left to act), giving SB the worst possible postflop position. 3-betting creates fold equity that flatting can't, and pushes the BB out of the pot. Modern solver output: 3-bet ~13%, flat only ~3% (typically pocket pairs that want to set-mine).
Range — the hands you play
- Value: TT+, AQs+, AKo
- Bluff: A5s-A2s, K9s-K6s mixed, suited connectors 76s/65s/54s
Key insights
- Sizing: 4x the BTN open (so 10-11bb total). Larger than BB's 3.5x because SB has to discourage BB squeeze frequency too.
- If SB flats: only with 22-55 to set-mine (rarely worth it at 100bb).
- BB will cold 4-bet vs SB 3-bet at ~6-8% frequency — SB's 4-bet defense is QQ+, AKs jam.
Frequently asked
Why does SB 3-bet wider than BB does?
Two reasons: (1) SB removing herself from the pot before BB acts shuts BB's wide flatting range out, capturing dead money from the BB; (2) SB has no other way to play marginal hands profitably — flatting is OOP vs both BTN and BB, which is brutal.
Should SB ever just flat-call vs BTN open?
Rarely — only with small pocket pairs (22-55) that want to set-mine and have implied odds to justify the call. Everything else either 3-bets or folds. SB's positional disadvantage against both BTN and BB makes most flatting unprofitable; the rake structure in online cash makes this even more pronounced.
What sizing should SB use for the 3-bet?
Roughly 4x the BTN open size — so against a 2bb min-open, around 8-9bb total; against a 2.5x, around 10-11bb. Larger than the BB's 3.5x sizing because SB has more dead money in the pot (BB is still left to act) and needs to discourage BB from squeezing wide vs a smaller SB 3-bet.