progressBig blind defense in MTTs
You get the best price at the table, so you defend much more than feels natural.
The big blind is the most defended seat in poker for one reason: price. You have already paid a blind, you close the action preflop, and in a tournament the antes have made the pot larger.
The price you get
Take an 8-max tournament with an ante of 12.5% of a big blind per player. A button min-raise to 2 BB leaves this in the pot before your call: his 2 BB, your 1 BB, the small blind's 0.5 BB and 1 BB of antes, which is 4.5 BB. You call 1 BB more to win 5.5 BB in total, so you need only 18.2% equity. That is why a hand as weak as 72s can profit from a call against a wide opener.
What the solution book does
Each cell shows fold / call / raise or all-in for the big blind facing a standard open with the small blind folded:
| Stack | vs UTG | vs CO | vs BTN |
|---|---|---|---|
| 15 BB | 26% / 66% / 8% | 21% / 59% / 20% | 21% / 56% / 23% |
| 20 BB | 27% / 65% / 8% | 16% / 67% / 17% | 15% / 62% / 23% |
| 30 BB | 28% / 65% / 7% | 15% / 70% / 15% | 9% / 69% / 22% |
| 40 BB | 30% / 64% / 6% | 20% / 66% / 14% | 12% / 69% / 20% |
| 60 BB | 30% / 64% / 6% | 23% / 64% / 13% | 13% / 67% / 20% |
| 100 BB | 35% / 59% / 6% | 26% / 60% / 14% | 26% / 54% / 20% |
Against the button at 30 BB the book folds only 9% of hands. Against UTG it folds 28%. An early-position open is a much stronger range, so the same big blind needs more.
How it changes with stack depth
- Under 15 BB the raises become all-in shoves. Against the button at 10 BB the book goes all-in with 21% of hands and calls with 47%.
- Around 20 to 30 BB calling dominates; 3-bets are rare and mostly shoves.
- At 40 BB and more a 3-bet to a small size appears with 17% of hands against the button, and the rest of the defence is calls.
What to take away
Compare your own numbers with the chart for the stack you play most. Practise it hand by hand in the free trainer:BB defence vs the button at 30 BB is a good first chart.
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Questions
How often should the big blind defend?
In our book the big blind folds roughly 8 to 15 percent of hands against a button open at 20 to 30 big blinds, and 25 to 30 percent against UTG.
Why can the big blind call so wide?
It has already paid a blind and closes the action, so the equity it needs to call is small, about 18 percent against a min-raise with antes.
Does ICM change BB defence?
Yes. Near payout jumps the big blind should fold more, especially against bigger stacks.
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progressGTO guides use our own solution book (v13, 8-max tournaments with ante, chip EV): an approximation of equilibrium with a modelled postflop, not an exact solution. Numbers are computed from the book and from the exact ICM model.
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