Button vs big blind is the single most common single-raised pot in poker. The button opens wider than anyone, and the big blind defends wider than anyone, so the spot comes up constantly in cash games, tournaments and Spins. If you're going to master one spot with GTO study, make it this one.
Preflop: why both ranges are wide
The button opens wide
With only the blinds left to act, and position guaranteed postflop, the button can open a large range profitably. At 100bb in 6-max cash that's typically around 40–48% of hands, and wider in formats with antes.
The big blind defends wide
The big blind has already posted 1bb, so it's getting a good price:
| Format | BTN open | BB calls | Equity needed |
|---|---|---|---|
| Cash, no ante | 2.5bb | 1.5bb into 5.5bb | ~27% |
| MTT with BB ante | 2bb | 1bb into 5.5bb | ~18% |
Being out of position means the big blind won't realise all its equity, so it can't defend everything that clears the price. But it defends a large share of hands, by calling and by 3-betting a mix of strong hands and well-chosen bluffs.
The most common leak in this spot is simple: folding the big blind too much.
Postflop: range advantage decides the strategy
After the call, the button has the stronger range overall. The big blind 3-bets many of its strongest hands, so its calling range is capped, with few top-end combinations. The button's range still contains all of them.
How much that matters depends on the board.
High, dry boards (e.g. A-high or K-high, unconnected)
These boards favour the button's range: it has more strong aces and kings, and the big blind has few. Solvers typically c-bet very often with a small size, since the big blind can't fight back much.
Low, connected boards (e.g. 7-6-4, 8-6-5)
These hit the big blind's range: it defends many suited connectors and small pairs, while the button has a lot of high cards that missed. Solvers check much more as the button here, and the big blind's check-raise becomes a major weapon.
Paired and monotone boards
Paired boards usually favour the preflop raiser and allow frequent small c-bets. Monotone boards compress equities and reduce betting frequency, since having the flush (or the big blind holding it) matters more than overall range strength.
| Board type | Who it favours | Typical BTN approach |
|---|---|---|
| A-high / K-high dry | Button | Bet often, small |
| Middling, connected | Closer to even | Mixed, more checks |
| Low, connected | Big blind | Check more, bet selectively |
| Paired | Button | Bet often, small |
| Monotone | Neutral | Bet less often |
Studying the spot
There are 22,100 possible flops (1,755 strategically distinct ones) and nobody memorises them all. Study by texture classes: learn how the button's c-bet frequency and size change from high-dry to low-connected boards, and how the big blind responds. That generalises to boards you've never seen.
A practical order:
- Preflop: button open range and big blind defence (call and 3-bet).
- Flop c-bet strategy by texture class.
- Big blind response: check-raise and float ranges on the boards that favour it.
- Turn barrels on the most common runouts.
Drill each layer with a GTO poker trainer until it's automatic, and check your own hands for the classic leaks with a hand history review. For the other common blind spot, see SB vs BB.
Frequently asked questions
How much equity does the big blind need to call a button open?
Against a 2.5bb open in a cash game without antes, about 27%. Against a 2bb open with a big blind ante, about 18%.
Should the button c-bet every flop against the big blind?
No. On high, dry boards that favour the button's range it c-bets often with a small size; on low, connected boards that favour the big blind it checks much more.
How many flops are there in poker?
There are 22,100 possible flops, which reduce to 1,755 strategically distinct ones. Players study by texture class rather than memorising individual flops.