Detailed Explanation of Cutoff CO Opening Range: Building Efficient Steal and Value Range

Position Scenario Description

The Cutoff (CO) sits one position before the Button (BTN) and is the last player to act with positional advantage. Since only the Button, Small Blind, and Big Blind remain to act, the CO can frequently use position to steal blinds or value raise. At the same time, the CO may face a re-raise from the Button, so the range needs to balance value and bluffs.

Recommended Range

Below is a typical CO opening range for a 9-handed full ring game (about 22%-25% of starting hands, assuming 100BB effective stacks). The actual range should be adjusted based on opponent dynamics.

Value Raises (Top ~8% of hands)

• Big pairs: TT+ (TT, JJ, QQ, KK, AA)
• Strong high cards: AQo+ (AQ, AK offsuit), AJs+ (AJ, AQ, AK suited)
• Small pairs can sometimes be slow-played but are usually raised.

Speculative & Semi-Bluffs (~10%-12% of hands)

• Medium-strong suited connectors: 76s+ (76, 87, 98, T9, JT, QJ suited)
• Small pairs: 22-99 (for set mining)
• Some suited gappers: ATs, KJs, QTs, J9s, T8s, etc.
• Weak suited aces: A2s-A5s (low suited aces with flush draw and straight potential)

Bluffs & Blind Steals (~5%-7% of hands)

• Weak offsuit high cards: KJo, QTo, JTo, etc. (can steal blinds when blind defenders are weak)
• Some suited connectors like 54s, 65s (good structure but weak hand strength)
• Rarely mix in A2o-A5o, but be cautious as they are easily dominated.

Note: The above ranges are examples only. In practice, adjust based on opponent style, stack depth, and table dynamics.

Range Construction Logic

Building a CO range considers:

1. Positional Advantage: The CO acts last postflop, so more speculative hands like small pairs and suited connectors can be played.
2. Blind Steal Value: Blind players have wider ranges, so the CO can loosen their raising range to exploit weak defenders.
3. Balance to Avoid 3bets: The CO faces frequent 3bets from the Button, so the range must include enough 4bet bluffs (e.g., A5s, KQs) to protect value hands.
4. Against Cold Calls from Blinds: When blinds call, the CO range should be more linear (strong and weak hands clearly separated), avoiding medium-strength hands that get dominated.

Adjustment Factors

• Opponent Style:
  • If the Button 3bets frequently, tighten the CO raising range and add some 4bet bluffs.
  • If blinds call too loose, widen the value range and reduce pure bluffs.
• Stack Depth:
  • Short stacks (<40BB): Reduce speculative hands, favor strong hands for all-ins.
  • Deep stacks (>150BB): Can add more suited connectors, but be mindful of pot control.
• Game Flow: If the table is generally passive, significantly widen the CO range to steal blinds.
• Tournaments vs Cash Games: In tournaments, due to ICM pressure, keep the CO range tighter to avoid marginal hands facing short-stack shoves.

GTO Reference

According to GTO solvers, for a 9-handed table with 100BB stacks, no antes, and standard raise size (2.5BB-3BB), the optimal CO opening range is about 22%-24%. The core includes:

• Top 4% strong hands (TT+, AQ+, AJs+)
• Middle ~8% connectors and small pairs (e.g., 76s-98s, 22-99)
• Remaining ~10%-12% structure hands and bluffs (e.g., suited aces, KXs, Q4s-Q9s, but excluding hands that are easily dominated)

GTO emphasizes balance: maintain the right ratio of value to bluffs so that opponent 3bets and calls do not become instantly profitable. Specific ranges can be calculated with solvers, but understanding the principles is sufficient for practice.

Practical Application

• Standard Raise Size: Typically 2.5BB-3BB. Use 2BB to steal when blinds are weak; use 3BB+ when opponents are tough.
• Responding to Button 3bets: 4bet with JJ+, AKs+; call with medium hands like AT, KQ; 4bet bluff with small pairs (e.g., A5s).
• Responding to Blind Calls: Postflop, use positional advantage to aggressively c-bet, especially on flops favorable to your range (e.g., flopped sets or flush draws).
• Blind Steal Techniques: When fold equity is high, use your weakest raising hands (e.g., JTo, K5s) to steal blinds, but anticipate whether the Button might isolate.

Remember, ranges are dynamic. Adjust based on real-time observations: if the Button 3bets too rarely, widen your steal range; if they 3bet too often, tighten up and prepare to 4bet.