Cutoff CO Opening Range Guide: From Theory to Practice

Position Scenario Explanation

The Cut Off (CO) is located to the right of the Button (BTN) and is the third-best position post-flop (after BTN and BB). The CO player acts after most players on the flop, turn, and river, with only the BTN and BB having later positions. Since there are 2–3 players yet to act before the CO (HJ, MP, etc.), and the BTN, SB, and BB follow, the CO’s opening range needs to balance value, stealing blinds, and protection.

Recommended Range (Standard 9-Handed, No Previous Limpers, 100BB Stack)

Generally, the standard CO opening range is about 22%–25% of hands, categorized as follows:

• Strong Value Hands: All pairs (22+), all suited aces (A2s+), all high suited connectors (T9s+), and AJo+, KQo+.
• Mixed Range: Some suited connectors (e.g., 76s, 87s), suited gappers (J9s, Q9s), and some weak Ax (e.g., A9o, A8o) and small suited connectors (54s+) can be added under appropriate conditions.
• Blind Stealing Hands: Include some suited broadways (KJs, QJs) and a few offsuit connectors (e.g., KTo, QTo) to balance the range.

Typical range example (about 25%): TT+, ATs+, KJs+, QJs, JTs, T9s, 98s, 87s, 76s, 65s, 54s, AJo+, KQo+, plus all pairs 22- 99, and A2s- A9s, K9s- KTs, Q9s, etc.

Range Construction Logic

The CO range is built on three core factors:

1. Position Advantage: The CO can control the pot post-flop and has stealing opportunities against the blinds, allowing a wider range of speculative hands.
2. Threat from Later Players: The BTN, SB, and BB may 3-bet, especially the BTN with a very favorable position, often re-raising with a wide range. Thus, the CO should avoid overly light opens that invite re-steals.
3. Unacted Players in Early Position: If players in earlier positions (MP, HJ) are still in the hand, the CO must be aware that they might hold strong hands.

Typically, the CO range places value hands (high pairs, strong aces) in the front, speculative hands (suited connectors, small pairs) in the back, and includes a moderate number of bluff 3-bets to balance.

Adjustment Factors

• Tight/Passive Early Players: If MP and HJ frequently fold, the CO can expand the opening range to 30%+, including more weak Ax and suited connectors.
• Aggressive Blinds: If the BTN or blind players often 3-bet, the CO should tighten the range, removing marginal hands (e.g., K9s, Q9s, 76s) and increasing the 4-bet frequency.
• Stack Depth: With deep stacks (200BB+), suited connectors and small pairs have higher implied odds, so more can be added. With short stacks (<40BB), reduce speculative hands and focus on value hands.
• Opponent Type: If the BTN is a calling station, the CO can open wider but must control the pot post-flop. If the blinds are aggressive, consider increasing steal frequency while incorporating 4-bets.

GTO Reference

According to GTO principles, the optimal CO opening range at 100BB depth is about 22–25%, with a typical raise size of 3BB (or 2.5BB against weaker blinds). Below is an approximate GTO preflop range allocation (not exact):

• Raising Range: Includes all pairs, suited aces, suited connectors (54s+), offsuit broadways (ATo+), etc., totaling about 300 combos (25%).
• Facing a 3-bet: The CO should defend about 70% of 3-bets, with a 4-bet range consisting of QQ+, AKs+, and a calling range of other strong hands (e.g., TT-JJ, AQ, KQs, etc.).
• Blind Stealing Strategy: When facing the blinds, the CO can raise individually to 2.5BB against the SB or BB, expanding the range to 35% to apply pressure.

These GTO values come from modern poker theory, but in practice, exploitative adjustments should be mixed in.

Practical Application

1. Standard Hand Example: CO holds A♥5♥, all players fold before, blinds unknown. Raise to 3BB. Flop K♠7♣2♦. If the opponent checks, c-bet 1/3 pot as a continuation bet, using the A high as a bluff.
2. Adjustment Example: If the BTN is an aggressive 3-bettor, the CO with T♠9♠ should fold rather than raise, as a 3-bet likely forces a fold.
3. Against a Calling Station: CO holds 98s, raises, flop is wet. If the opponent checks, use a double barrel to generate fold equity.
4. Deep Stack Raise: With effective stacks of 200BB, the CO can raise to 3.5BB and expand the range to include suited connectors (65s+) to exploit implied odds.

In summary, the CO opening range should be flexibly adjusted based on opponent dynamics, but the core principle is to maintain a balance between value and bluffs while leveraging positional advantage.