PokerSolver
PokerSolver/4-max · 100bb · SB 0.5bb · ante 0.16bb · 5% rake, cap 4.8bb/BB vs CO 4-bet 20.7bb

BB vs CO 4-bet 20.7bb

4-max · SB 0.5bb · ante 0.16bb · 5% rake, cap 4.8bb (blinds 0.5/1bb, ante 0.16bb) · 100bb · CO opens 3bb, BB 3-bets to 9bb, CO 4-bets to 20.7bb · Big blind to act

4-max · 100bb · SB 0.5bb · ante 0.16bb · 5% rake, cap 4.8bbChange game
Stacks (bb), if they differ
Pot 30.84bbYour cards?
9bb
20.7bb
0.5bb

Tap your two cards.

Big blind's range

462 of 1,326 combos get here
Fold 69.1%Call 17.6%All-in 99.84bb 13.3%
Tap a hand, or type one above, to see its exact mix.

What is the GTO play for the big blind (BB) when CO opens 3bb, BB 3-bets to 9bb, CO 4-bets to 20.7bb in 4-max · SB 0.5bb · ante 0.16bb · 5% rake, cap 4.8bb at 100bb?

CO opens 3bb, BB 3-bets to 9bb, CO 4-bets to 20.7bb in 4-max · SB 0.5bb · ante 0.16bb · 5% rake, cap 4.8bb, 100bb: the big blind (BB) folds 69.1%, calls 17.6% and goes all-in 99.84bb 13.3%. Always call: 55, AJs-AQs, KQs, KTs, 87s, 76s, 65s, 54s. Always all-in 99.84bb: QQ-KK, 88-TT, AKs, AKo. Mixed: AA, JJ, 66-77, ATs, A8s, A4s-A5s, KJs, JTs, T9s, 98s, 75s, AQo.

Always fold
A6s-A7s, A2s-A3s, K3s-K9s, Q3s+, J5s-J9s, T6s-T8s, 96s, 85s-86s, 63s, 43s, A8o, A5o, K9o+, QTo+, JTo, T9o
Always call
55, AJs-AQs, KQs, KTs, 87s, 76s, 65s, 54s
Always all-in 99.84bb
QQ-KK, 88-TT, AKs, AKo
Mixed
AA, JJ, 66-77, ATs, A8s, A4s-A5s, KJs, JTs, T9s, 98s, 75s, AQo
Settings: 4-max · 100bb · SB 0.5bb · ante 0.16bb · 5% rake, cap 4.8bb (small blind 0.5bb, big blind 1bb, an ante of 0.16bb from every player, 100bb stacks, 5% rake capped at 4.8bb; no rake when no flop is dealt). Solver: HoldemResources Calculator (HRC) (HRC CI 24.66). A jackpot fee on bigger pots is not in this solve, so lines that build big pots may be slightly too loose. Bet sizes are the solved ones; a size that is not here plays like the nearest one.

Fits exactly: no game we have checked.

Close: CoinPoker cash with antes NL50 (rake before the flop in 3-bet pots there, none here).

Rake sources: the ante from 93 of our own CoinPoker hands at $0.25/$0.50 with a $0.08 ante, played 2026-09-30; the caps and the preflop rule from coinpoker.com/games/texas-holdem/, fetched 2026-10-31.