Cutoff CO Opening Range Explained: GTO and Exploitative Strategies

Position Scenario Description

The cutoff (CO) is the position after the under-the-gun position and before the button in six-max or full-ring games. Since it is adjacent to the button and only the button and blinds act after it, the CO has high steal value and opportunities to control the pot. The CO's opening range is typically wider than early positions, but still needs to account for squeezes from late position players and blind defense.

Recommended Range (Standard GTO Reference)

The following is a typical CO opening range for six-max at 100bb depth (approximately 22%–25% of hands):

• Value Hands: JJ+, AKo, AKs, AQo+ (about 5% of hands)
• Medium Strength: ATs+, KTs+, QTs+, JTs, T9s, 98s, 87s, AJo, KQo (about 7% of hands)
• Speculative Hands: 88–22, A9s–A2s, K9s–K8s, Q9s, J9s, T8s, 97s, 86s, 76s (about 10% of hands)
• Mixed Portion: A5o, A4o, KJo, QJo, JTo (about 3% of hands; can be selectively raised or folded)

Note: The above range is based on common GTO solver results and can be fine-tuned in practice.

Range Construction Logic

The CO range is built on several core principles:

1. Leverage Position: The CO has postflop position, allowing decisions after seeing actions from the button and blinds, so more speculative hands (small pairs, suited connectors) can be included.
2. Balance Value and Bluffs: Hands like A5o, A4o are included as weak Ax hands for preflop raise and 3-bet bluffs; they have value when they flop an Ace.
3. Avoid Over-Exploitation: A range too narrow encourages blinds to defend wider; a range too wide invites squeezes from the button and blinds. The standard range aims to make opponents' 3-bets and calls unprofitable.

Adjustment Factors

In practice, adjust the range based on opponents and dynamics:

• Passive Opponents (blinds call frequently): Tighten the range, favoring value hands (e.g., drop K9s, Q9s).
• Aggressive Opponents (blinds 3-bet often): Widen the range, especially adding speculative hands to leverage postflop playability. However, be prepared to fold frequently to 3-bets.
• Button Player Style: If the button 3-bets frequently, reduce the opening range and increase 4-bet bluffs; if the button calls often, add more suited connectors.
• Stack Depth: Short stacks (<50bb) tighten the range, focusing on big cards. Deep stacks (>150bb) widen with more suited connectors and small pairs to chase large pots postflop.
• Tournament Stage: Near the money or final table, consider ICM pressure and reduce marginal raises.

GTO Reference

According to mainstream GTO solvers (e.g., PioSolver, MonkerSolver), at six-max 100bb depth, the CO opening range is about 22%–25%, with roughly 60% of raises sized at 2.5bb–3bb (depending on blind size).

• Facing a 3-bet, the CO should fold about 50%–60% of weak hands, 4-bet bluff with JJ+, AK, and some suited connectors.
• When called, the postflop strategy tends toward high-frequency continuation betting (about 70% of flops), especially with draws or top pair.

Note: GTO is a baseline; exploitative adjustments are often more effective against human opponents.

Practical Application

Example 1: Cash Game Six-max, blinds $2/$5, effective stack $500. CO holds T9s. The two players behind are loose. You raise to $15, button calls, blinds fold. Flop: K♣8♠6♦. You c-bet $20, button folds. Here, T9s has equity but can bluff postflop, fitting the GTO range.

Example 2: Tournament Blinds 500/1000, ante 100. CO stack 30,000, button stack 20,000 and is tight. You hold A5o, raise to 2200, blinds fold, button calls. Flop: A♠T♥3♣. You bet 3000, button folds. A5o is weak but profitable when flopping an Ace, and a tight opponent is less likely to call.

Common Mistakes:

• Not widening the range when the blinds are very tight, missing steal opportunities.
• Frequently raising marginal hands (e.g., K8o) against loose blinds, leading to postflop difficulties.
• Robotically following a range list without considering opponent reactions.

Summary: The CO is one of the most profitable positions. Adjust the range flexibly based on the situation to balance value and speculation.