Cutoff CO Opening Range Guide: How to Exploit the Blinds Precisely

Positional Scenario Description

Cutoff (CO) is positioned before the Button (BTN) and after the Hijack (HJ). In a 6-max game, CO is the third player to act (UTG, HJ, CO, BTN, SB, BB). Since only BTN and the blinds remain to act after CO, and BTN has the final position, CO must contend with BTN's 3-bet and the blinds' defense. However, compared to earlier positions, CO's raising range can be significantly wider because fewer players are left to act.

Typical scenario: blinds 1/2, effective stack 100BB. CO opens for 2.5BB. BTN, SB, BB call or fold.

Recommended Range (Typical Balanced Range)

The following is a balanced open-raising range for 100BB deep stacks with no special reads (approximately 24%-28% of starting hands):

• Strong hands: 99+ (pairs), AJ+ (high cards), KQ+ (suited/offsuit)
• Medium strength: A2s-A5s (small suited aces), A9s-AJs (high suited aces), K9s-KJs (suited K), Q9s-QJs (suited Q), JTs-J9s (suited J), T9s (suited T), 98s (suited 9)
• Partial speculative hands: A8s-A6s (medium suited aces), K8s (suited K), Q8s (suited Q), J8s-T8s (suited connectors), 76s-65s (small suited connectors)
• Note: The range does not include all suited connectors; for example, 54s, 43s are usually folded. It also excludes weak offsuit hands like A9o, KTo unless there is a special read.

Range Construction Logic

CO's raising range needs to balance value hands and bluffs, while considering the following principles:

1. Positional advantage: CO has a greater positional advantage over the blinds, so they can play more speculative hands, especially suited connectors and suited aces, as they are easier to draw or make hands post-flop.
2. Defending against BTN's 3-bet: BTN is the only player who can maintain position post-flop, so CO needs to keep some strong hands (e.g., TT+, AQ+) to resist BTN's 3-bet, while using some medium hands to call or 4-bet.
3. Blinds' defense: The blinds typically defend with about 10-18% of hands. CO should select hands that have decent equity against the blinds' calling range. For example, suited aces and small pairs are favorable against the blinds' wide range.
4. Frequency balance: To avoid being exploited, CO's raising frequency should be between 20-30%, increasing as position moves later. CO's open-raising frequency is typically around 25%.

Adjustment Factors

The actual range should be dynamically adjusted based on the following factors:

• Opponent tendencies: If BTN is an aggressive 3-better (about 10%+), tighten CO's range to 20-22% and use more 4-bets; if BTN and the blinds are passive, widen it to 30%+.
• Stack depth: In shallow stacks (<50BB), reduce small suited connectors and weak suited aces, increase big pairs and high cards; in deep stacks (>150BB), add more speculative hands, such as all suited connectors (54s+), and even some offsuit connectors.
• Game dynamics: If players in early positions frequently fold, CO can be more aggressive; if someone limps in front, CO should call or raise wider.
• Player reads: If the blinds fold too often (<10% defense), CO can raise any two cards; if the blinds call or 3-bet too frequently, tighten the range.

GTO Reference

According to GTO theory, with 100BB and no ante, CO's optimal raising frequency is about 25-28%, with a value-to-bluff ratio of approximately 40%:60%. A typical GTO range includes:

• All pairs (22+) are usually worth raising, but 22-55 may need to fold facing a 3-bet.
• All Ax suited (A2s+) are raised, as well as A9o+ (offsuit).
• Suited connectors are raised from 54s+, but below T9s usually only the suited versions.
• K9s+, Q9s+, J9s+, T8s+, etc.

Note: GTO references are not absolute; in practice, exploitative deviations are more profitable.

Practical Application

1. Exploiting Passive Blinds: When the big blind and small blind fold rate exceeds 75%, the CO can raise with about 40% of hands (including any two suited cards, all Ax, Kx, Qx, etc.), but be aware of BTN's 3-bet frequency.

2. Facing an Aggressive BTN: When the BTN frequently 3-bets (e.g., over 8%), the CO should increase 4-bet bluffs (such as A5s, K8s) and tighten the calling range to avoid being frequently exploited.

3. Short Stack Strategy: When the CO's own stack is less than 40 BB, only raise strong hands like TT+, AQ+, AJs+, and be prepared to shove, avoiding speculative hands that lead to postflop difficulties.

4. Using Position to C-Bet: CO has a positional advantage postflop. Even with a wider range, you should c-bet with high frequency on favorable board textures (e.g., low dry boards) to represent a strong range.

5. Adjustment Example: In a full-ring game (9 players), the CO range should be tightened by about 3-5 percentage points compared to 6-max because there are more players behind; in heads-up (HU), the CO is the button, so the range can be widened to 50%+.

Mastering dynamic range adjustments in the CO position allows you to build an advantage preflop and apply continuous pressure postflop using position. Avoid mechanically applying a fixed range; observe opponents and record adjustments to become a consistent winner.