The BB (Big Blind) is the seat to the left of the small blind, and it is forced to post one big blind before the cards are dealt.
It is the only seat at the table where the money is already in and the decision comes last preflop. That makes the big blind’s arithmetic completely different from every other seat: the other seats are asking “is this hand worth getting involved with”, while what the big blind has to decide is “is this hand worth putting in a bit more” — you can also think of it as whether you need to defend the one big blind you have already put in.
1. What Makes This Seat Different
| BB | |
|---|---|
| Preflop | Acts last, after seeing everyone else’s action |
| Postflop | Acts 2nd; in position only against the small blind |
| Money already on the table | 1bb |
| Main spot | Defence: someone opens, everyone else folds, and it is on you |
If everyone folds, the small blind included, the big blind simply takes the pot — the big blind never gets to “open”, and all of its work is defence.
2. Why the Defending Range Is So Wide
Your opponent raises to 2.5bb on the button and the small blind folds. You have already put in 1bb, so another 1.5bb lets you play for a pot of 5.5bb — close to 11 to 3, which means winning about 27% of the time is enough to break even. You do not need much of a hand for a flop to be worth seeing. (For how the odds are worked out, see how to work out pot odds.)
The cost is that you are out of position after the flop almost every time: apart from the small blind, whoever opened acts after you on every street after the flop. So the big blind’s defence is wide because it is cheap, not because it is easy to play.
3. Defence Depends on Who Opened
Big blind defence does not use the same range against every opponent; it is decided by who opened. These are the defaults in RushCraft’s preflop trainer (calls plus 3-bets as a share of all starting hands):
| Opener | Call | 3-Bet | Total |
|---|---|---|---|
| UTG | 8.0% | 1.7% | 9.7% |
| MP | 22.2% | 1.7% | 23.9% |
| CO | 27.6% | 3.3% | 30.9% |
| BTN | 27.6% | 5.3% | 32.9% |
| SB | 47.5% | 4.1% | 51.6% |
Against the tight 11.2% range of Under the Gun (UTG), you defend less than one hand in ten; against the wide range of the Small Blind (SB), where you also have position after the flop, you defend more than half. What you are defending against is not your own hand but your opponent’s range. The ten sets of hands are laid out in the range charts under big blind calling and big blind 3-betting.
4. The Most Common Mistakes
1. Folding too often. Thinking “I’ll be out of position after the flop”, you play the big blind like any other seat and only defend with good hands. The players in late position will notice your big blind is easy to steal from, and they will steal it every orbit. How often you fold to a steal (Fold BB to Steal) should be roughly 55% or lower.
2. Calling too often. The opposite: thinking “I’ve already put money in”, you call with everything. Against an under-the-gun open your price is just as good, but your opponent’s range is much stronger, and the weak hands you call with are often dominated after the flop.
3. Only calling, never 3-betting. Big blind defence has two buttons. If you only call, you see every flop out of position; 3-betting the strongest part of your range ends some pots before the flop and keeps the late-position players from reading you (see what a 3-bet is).
The big blind in one sentence: the best price at the table and nearly the worst position — so how much you defend depends on which position the opener is in.
- Previous seat: the Small Blind (SB)
- Back to the first seat: Under the Gun (UTG)
- The whole series: the position guide
To see the other spots the big blind runs into (facing limpers, getting 3-bet, multiway pots), read on in the complete guide to preflop play.