Defending the big blind

The button raises to 2 BB. You are in the big blind with 1 BB already in the pot. Folding is the most common mistake beginners make here, and it is expensive: the big blind is a losing seat for everyone, and every unnecessary fold deepens the loss.

The price you are offered

When the small blind folds, the pot holds 3.5 BB: your blind, half a blind from the small blind and the button’s 2 BB raise. Calling costs 1 BB to play for 3.5. You need to win only about 22 % of the time for the call to break even.

Almost every hand has 22 % equity against a wide button range. That is why the reference range defends most hands, including many that look weak. On top of that you close the action: nobody can raise behind you.

When to 3-bet

Your strongest hands do not want to call. Big pairs and big aces 3-bet: they build the pot while ahead, and they take the initiative back from the button.

The 3-bet comes in two forms. A raise to a size with the hands that want to be called and can play a big pot: AA to TT, AKs, AQs. A shove with the hands that would rather not see a flop out of position but do well when the button folds: AKo, AQo, AJo and most small pairs. The reference range also 3-bets a hand like A8o as a bluff with a plan: if the button shoves, it folds.