Introduction

The check-raise is the big blind's main weapon on the flop. You defend against an open, check to the preflop raiser, they continuation-bet, and you raise. It wins pots against wide c-betting ranges, builds the pot with your strong hands, and stops the raiser from betting any two cards for free.

Most players get it wrong in the same direction: they save the check-raise for monsters and the occasional big draw, so they raise rarely and their raises are easy to read. A solver check-raises far more often than that on the right boards, with a range that looks nothing like "sets and nut draws" — and far less often on the wrong ones.

This guide gives you a process for deciding when to check-raise, with which hands and at what size. Every frequency in it comes from one solver tree: 6-max cash, 100bb, button opens 2.5bb, big blind calls, the button c-bets either 25% or 80% of the pot. The full data — ten flops with grids — is in our check-raise study.

Key Concepts

A check-raise attacks a range, not a hand

You are not raising because of what the button holds this time. You are raising against everything it could be betting. When the button c-bets almost its whole range, much of that range is weak, and a raise wins the pot often. When it c-bets a narrow, strong range, a raise wins far less. That is why the c-bet size — which tells you how wide the button is betting — matters more than anything else in this guide.

Range advantage and nut advantage

Range advantage is about whose range is stronger overall on this board. Nut advantage is about who holds more of the very best hands. The big blind check-raises most when the button's range is wide and weak, and least when the button has the nuts and the big blind doesn't.

High boards are the clearest case. On A♠ K♦ 5♦ or K♠ 9♠ 4♠, the button holds every AK and most big pairs — hands the big blind would have 3-bet preflop. With few strong hands of its own, the big blind has little to raise for value, and so it can only raise a few bluffs. In this solve it check-raises those boards just 7–10% of the time against a small c-bet.

Check-raise ranges are polarised

On every board, the solver's check-raising range is built from two ends: strong hands (two pair, sets, trips, straights) and hands that would rather raise than call — draws, and hands with backdoor potential. Medium-strength hands, such as top pair with a good kicker, mostly call. They beat the button's bluffs, and raising them only folds out the hands they beat.

What changes from board to board is the bottom end. On connected boards it is straight draws. On dry and paired boards, where there are few draws to raise, it is suited connectors and suited aces with backdoor potential.

Two sizes, chosen by board

This tree gives the big blind two raise sizes: 2.5 times the bet and 4.5 times the bet. Against the small c-bet, that is a raise to 3.45bb or 6.21bb into a 5.5bb pot. The choice depends on the board, not on your hand: small raises where little changes on the turn, big raises where the next card can change who is ahead.

Step-by-Step Guide

Step 1: Read the c-bet size

Start with the size of the bet you are facing. On all ten flops in the solve, the big blind raises a 25%-pot c-bet more often than an 80%-pot one — on 8♠ 8♦ 3♣, 36% against 24%; on K♠ 9♠ 4♠, 7% against 1%. A small bet means a wide range and a cheap raise. A big bet means a stronger range, and calling or folding becomes the default.

Step 2: Classify the board

Then place the flop in one of five groups. These are the big blind's check-raise frequencies against each c-bet size:

Board type	Examples	vs 25% c-bet	vs 80% c-bet
Paired	J♠ J♦ 4♣, 8♠ 8♦ 3♣	27–36%	13–24%
Dry, king-high or lower	K♠ 7♦ 2♣, 9♠ 5♦ 2♣, 6♠ 4♦ 2♣	20–24%	9–11%
Dry, ace-high	A♠ 7♦ 2♣	17%	8%
Connected	Q♠ J♦ T♣, 7♠ 6♦ 5♣	16–18%	10–13%
High two-tone, monotone	A♠ K♦ 5♦, K♠ 9♠ 4♠	7–10%	1–2%

Notice the order. Paired and dry boards get check-raised more than connected ones, not less. Those are the boards where the button c-bets small with nearly its whole range, and a range that wide is the easiest to attack. The common advice to "check-raise wet boards more" does not hold up against the same bet size.

Step 3: Pick your value hands

Your strongest hands raise most of the time. On A♠ 7♦ 2♣ against a small bet, the big blind raises 77 and 22 every time and A7o 97%. On 8♠ 8♦ 3♣, pocket threes raise 98%.

Two exceptions are worth knowing:

Top pair with a good kicker usually calls. On A♠ 7♦ 2♣, AJo raises only 6% of the time; on K♠ 7♦ 2♣, KQo raises 46%. These hands are strong enough to call down and do their best work keeping the button's bluffs in.
Some strong hands call because the board is dangerous to them. On K♠ 9♠ 4♠, a set of nines calls 99% of the time — on a monotone board a set is not the nuts, and raising it builds a pot against flushes. On 7♠ 6♦ 5♣, a made straight with 4-3 raises only half the time, because 9-8 makes a bigger one.

Step 4: Pick your bluffs

The best bluffs are hands that are poor calls but have something to improve to:

On connected boards, raise your straight draws, especially the ones with a pair. On Q♠ J♦ T♣, pocket nines (a pair plus an open-ended draw) raise 96% and A9s raises 99%.
On dry and paired boards, raise suited connectors and suited aces with backdoor potential. On A♠ 7♦ 2♣, 65s raises 88% and 85s 73%; on 8♠ 8♦ 3♣, 97s raises 94%. Hands like these have no pair and no straight draw yet, but they can improve on the turn — which is why they make up 39–47% of the check-raises on boards like K-7-2, J-J-4 and 8-8-3.

Random offsuit hands with no backdoors are not the bluffs. The solver's bluffs on dry boards are overwhelmingly suited, connected hands that can turn into something.

Step 5: Pick your size

Against a 25% c-bet:

Dry and paired boards: lean small. The 4.5× raise is only 27–51% of check-raises on J♠ J♦ 4♣, 8♠ 8♦ 3♣, K♠ 7♦ 2♣ and A♠ 7♦ 2♣.
Connected and draw-heavy boards: go big. On Q♠ J♦ T♣, 9♠ 5♦ 2♣, 7♠ 6♦ 5♣ and A♠ K♦ 5♦, 87–96% of check-raises use the 4.5× size. The turn can change everything, so the big blind charges the maximum while its draws still have fold equity and its strong hands are still ahead.

Use the same size for every hand you raise on a given board. If your value hands and bluffs use different sizes, the size gives your hand away.

Step 6: Plan the turn before you raise

Before you raise, know what you will do when you are called. Your strong hands keep betting. Your draws continue on the turns that improve them or that hurt the button's range, and give up on the ones that don't. Your backdoor bluffs need to pick up something — a flush draw, a straight draw, a pair — to keep going. A flop check-raise without a turn plan turns into a pile of guesses one street later.

Practical Examples

All four examples are the same spot: big blind defends against a 2.5bb button open, 100bb deep, 5.5bb pot on the flop.

Example 1: A♠ 7♦ 2♣ — a dry ace-high board

Against a 25% c-bet: the big blind check-raises 17% of its range, splitting evenly between the two sizes. Sets raise every time and A7o 97%. Weak-kicker aces mostly call: A2s raises 20%, ATs and A9s 23%. The bluffs are backdoor hands — 65s at 88%, 85s at 73%.

Against an 80% c-bet: the frequency drops to 8%. Sets still raise almost every time (77 at 92%, 22 at 96%), but A7o is down to 47% and 65s to 44%; ATs no longer raises at all.

The lesson: the same board, two different answers. The bet size changed the strategy more than the cards did.

Example 2: 8♠ 8♦ 3♣ — a paired board

This is the most check-raised board in the solve: 36% against a 25% c-bet. Pocket threes (a full house) raise 98%. The rest of the range is built from hands that can improve: 97s raises 94%, T9o 70%, K8o (trips) 82%. Two-thirds of the raises use the small size, because there is little for the turn to change.

Example 3: 7♠ 6♦ 5♣ — a connected board

The big blind check-raises 18% against a 25% c-bet, and 89% of those raises are the big size. Overpairs with straight draws raise every time (99 and 88). Sets mostly raise: 77 at 87%, 55 at 63%. 98o, the nut straight, raises 79%; 4-3 suited, a smaller straight, only 50%. Q8s, with an open-ended straight draw and an overcard, raises 90%.

Example 4: K♠ 9♠ 4♠ — a monotone board

The big blind barely check-raises: 7% against a 25% c-bet, 1% against an 80% one. Even a set of nines calls 99% of the time, and pocket fours raise only 39%. On a board where the button can easily hold a flush, raising builds pots the big blind does not want.

Common Mistakes

Saving the check-raise for monsters

If you only check-raise sets and two pair, you raise a few percent of the time on boards where the solver raises a quarter to a third of its range. Against small c-bets on dry and paired boards, you are leaving a lot of pots uncontested.

Raising big c-bets as often as small ones

An 80%-pot c-bet comes from a stronger range. On most boards the solver raises it less than half as often as a 25% bet. Treat a big bet as a reason to tighten up, not as a dare.

Raising top pair, good kicker on reflex

It feels like protection. Usually it just folds out the hands you beat and gets called by the hands that beat you. The solver mostly calls with these hands.

Bluffing with hands that have nothing

The solver bluffs a lot on dry boards, but with suited, connected hands that can improve. Raising offsuit junk with no backdoors is not the same play.

Raising sets on monotone boards

A set on K♠ 9♠ 4♠ is not the nut hand. The solver calls with a set of nines 99% of the time and raises pocket fours only 39%. Raise sets on reflex and you are building pots that a flush wins.

Giving up after the check-raise is called

A called check-raise is not a failure. Your range still holds strong hands and draws, and many turn cards are good for it. Plan your turn before you raise (Step 6), and keep betting the hands that earned it.

Advanced Tips

Adjust to how your opponent c-bets

Everything above assumes the button c-bets correctly. If a player c-bets small with almost everything, attack them harder than the solver does — their range is even weaker than equilibrium. If a player only c-bets strong hands, cut back your bluffs, because they will rarely fold. Against a player who folds too often to check-raises, add bluffs; against one who never folds, raise for value only and call with your draws.

Stack depth changes the picture

These frequencies are for 100bb stacks. With shorter stacks, a check-raise commits you to the pot much sooner, so bluffs lose value and the range shifts towards hands that are happy to get all-in. With deeper stacks there is more room to manoeuvre on later streets.

Delayed check-raises

Some hands that call the flop become good check-raises on the turn, once the turn card has shifted the ranges. Calling the flop with a draw and raising a good turn card keeps your flop calling range stronger and makes your turn raises harder to read.

Use your blockers

When choosing between two similar bluffs, prefer the one holding cards the button needs to continue. A card that blocks the button's strongest hands or best draws makes it more likely to fold to your raise.

Summary

The c-bet size is the biggest factor: the big blind raises a 25%-pot bet far more often than an 80%-pot bet on every board.
Paired and dry boards get check-raised the most (17–36% against a small bet); connected boards less (16–18%); high two-tone and monotone boards hardly at all (7–10%).
Check-raise ranges are polarised: strong hands plus hands that would rather raise than call. Top pair, good kicker mostly calls.
Bluff with draws on connected boards and with suited, backdoor hands on dry boards — not with hands that cannot improve.
Raise small on dry and paired boards, big on connected ones, and use one size for every hand on a given board.
Be careful with sets on monotone boards, and plan the turn before you raise.

For the full data behind this guide — all ten flops, with range grids and hand-by-hand results — read the check-raise study. The other side of the same spot is in our flop c-bet study, the button's strategy on many more boards is in the c-bet charts, and the range the big blind brings to the flop is on the big blind vs button defense chart.

How to Check-Raise the Flop