ConceptsPreflop
Blind defence
Defending the blinds against an open: a great price, paid for by playing out of position.
What it is
The big blind already has 1 bb in the pot and closes the action preflop, so calling an open costs less than it does for anyone else. That discount is why the big blind defends far more hands than any other seat calls.
The small blind is different: it is out of position against everyone, including the big blind still to act behind it, and it does not close the action. From the small blind most defence is a 3-bet or a fold.
Why it matters
The price depends on the open size. Against a 2 bb open the big blind needs about 22% equity, against 2.5 bb about 27%, against 3 bb about 31%.
Equity is not everything: out of position, hands realise less of it. Hands that make strong hands — suited, connected — defend wider than offsuit hands with weak kickers.
Folding too much from the big blind is one of the most common and most expensive preflop leaks, because the blinds are posted every orbit.
The maths
The equity the big blind needs equals the call divided by the pot plus the call, the pot including the open.
Worked example
J♣5♦ against a button open
The button opens and the small blind folds. Against the illustrative button range on these pages, J♣5♦ has about 36% equity.
- Against a 2.5 bb open: the pot is 2.5 + 0.5 + 1 = 4 bb and the call is 1.5 bb, so the price is 1.5 / 5.5 ≈ 27.3%.
- Against a 2 bb open: the pot is 3.5 bb and the call 1 bb — 1 / 4.5 ≈ 22.2%.
- Suppose J♣5♦ realises 65% of its equity out of position: 0.36 × 0.65 ≈ 23.4%.
- That is short of 27.3% but above 22.2%.
Fold it to the bigger open, defend against the min-raise. The open size moves the bottom of the big blind's range, and the realisation factor — an assumption here — decides where.
Try it
Set the pot and the call for different open sizes and see the price the big blind is getting.
Common mistakes
- Folding too often from the big blind against late-position opens.
- Calling too much from the small blind, which is out of position and does not close the action.
- Defending the same range against an under-the-gun open as against a button open.
- Ignoring the open size.
Related concepts
- Pot oddsThe share of the final pot a call costs — and so the equity a call needs to break even.
- Equity and equity realisationEquity is your share of the pot if every card were dealt now; realisation is how much of it you actually collect.
- Stealing the blindsOpening from the late seats to win the blinds: a bet that is profitable even when it fails a lot.