Blind Defense

Also known as: defending the blinds, big blind defense, BB defense

Continuing — by call or 3-bet — against a steal or open when you're in the small or big blind and already posted.

Blind defense is how the small blind and especially the big blind respond to an open raise. The big blind gets a structural discount: you've already posted 1bb, so you're getting a better price to call than any cold-caller. Against a 2.5bb open into a pot of 4bb (with the SB's 0.5bb), you call 1.5bb to win 4.5bb — pot odds of \(\dfrac{1.5}{4.5+1.5}=0.25\), so you need about 25% equity (before adjusting for poor OOP equity realization).

Because of this price, BB defending ranges are wide — frequently 40%+ against late-position steals — built from suited junk, suited connectors, low pocket pairs, and offsuit broadways, plus a polarized 3-bet region. You defend wider against smaller opens and against late positions (whose ranges are weaker), tighter against early-position opens and large sizings.

The correction most pools need: you are not obligated to hit MDF preflop, because you realize equity poorly OOP and the opener has the lead. In MTTs, ante and BBA structures add dead money that widens correct defense further.