Defending the blinds, and blind against blind

In this lesson

• Defend the big blind according to the price you are getting.
• Explain why the small blind prefers raising to calling.
• Play blind versus blind from both seats.
• Adjust when both blinds are the same size and the discount disappears.

Read first: Facing an open: fold, call or 3-bet · Advice, not a lock: every lesson opens.

Concepts used: Blind defence, Stealing the blinds, Pot odds

The big blind's discount

The big blind has already paid 1 bb and is the last to act preflop. When the small blind folds, it calls the open minus that 1 bb into a pot that already holds everything. Against a 2.5 bb open that is 1.5 bb into 4 bb: it needs about 27.3%. Against 2 bb it needs about 22.2%, against 3 bb about 30.8%.

No other seat gets that price, and no one can raise behind the big blind. That is why it defends more hands than any other seat calls.

Equity has to be realised

The price is not the whole story. The big blind plays every street out of position, so its hands realise less equity than they hold. Hands that make strong hands, such as suited and connected cards, realise more; offsuit hands with weak kickers realise less.

The opener's seat matters as well. Against an early-seat open the big blind defends far fewer hands than against a button open, even at the same price. Against wide late opens it also 3-bets more, to about four times the open: 10 bb against 2.5 bb.

The small blind: raise or fold

The small blind is out of position to everyone, including the big blind still to act behind it. Facing an open it gets a worse price than the big blind and does not close the action, so most of its continuing hands 3-bet rather than call.

Blind versus blind

When everyone folds to the small blind, only the big blind is left. Rail's charts give the small blind three options here: fold, complete for 0.5 bb, or raise to 3 bb. The big blind behind a completion can check or raise to 4 bb.

The raise risks 2.5 bb more to win the 1.5 bb in the middle, so it needs 2.5 / 4 = 62.5% folds as a pure steal, the same as a 2.5 bb button open. The completion costs 0.5 bb into a pot of 1.5 bb, a price of 0.5 / 2 = 25%, but it lets the big blind act last with position.

Both ranges are wide in blind versus blind, so hands that would be easy folds against an early open become playable. The big blind's position makes it the more comfortable seat after the flop.

Equal blinds

Some live games use equal blinds: the small blind posts as much as the big blind. That removes the small blind's discount and gives the table more to steal. With 1 bb in each blind, a 2.5 bb button open risks 2.5 to win 2.

The small blind now defends like a second big blind: against a 3 bb open it calls 2 bb into 5 bb, needing 2 / 7 ≈ 28.6%. Rail's charts are built for 0.5/1 blinds, so this game is not in the drills; adjust by the price.

Rules of thumb

• The big blind defends wide because of the price: about 27.3% against a 2.5 bb open.
• Defend tighter against early opens than late ones, even at the same price.
• From the small blind, facing an open, 3-bet or fold most of the time.
• Blind versus blind, both ranges are wide and the big blind has position.
• With equal blinds there is more to steal and the small blind defends like a big blind.

When they break

• Against openers who barrel relentlessly, the big blind realises even less; tighten the bottom of the defence.
• Against a small blind who completes and then plays passively, the big blind can raise its completions more.

Example hands

Practice

The lesson is mastered when every exercise below that Rail can grade is passed. Missed items come back later as review cards.