Cutoff CO Opening Range Guide: From Theory to Practice

Scenario Description

The Cutoff (CO) is the position after under the gun and before the button in six-handed or nine-handed tables. In the preflop action order, CO is the last player with positional advantage (no position after BTN). Therefore, the CO opening range is typically wider than early positions but tighter than the BTN. The main goal of CO is to use positional advantage to steal blinds or build a value range, while being vigilant against BTN's 3-bet or calls.

Recommended Range

The following is a typical CO opening range (assuming 6-handed, no previous limpers, blinds unknown):

• Pocket Pairs: All pairs (22+)
• High Cards: A9o+, KTo+, QJo+, JTo (partial)
• Suited Aces: A2s+ (all suited aces)
• Suited Connectors: 54s+, 65s+, 76s+, 87s+, 98s+, T9s+ (and some J9s, Q9s, K9s)
• Suited Gappers: J8s, T8s, 98s (already included), 86s+, 75s+, 64s+ (chosen based on positional aggression)
• Offsuit Hands: Usually only high cards; low offsuit hands are folded

Overall range accounts for about 22%-27% of all hands (adjust based on table dynamics).

Range Construction Logic

CO range construction is based on three core factors:

1. Position Advantage: CO is generally in a favorable position postflop (unless BTN calls), allowing for more speculative hands like medium and small pairs and suited connectors. These hands yield high returns when they hit strong hands on the flop.
2. Blind Stealing Potential: CO has only the BTN and blinds behind, and the blinds often have a tendency to call or defend. CO can raise to steal blinds, so the range must include enough bluff hands (e.g., low suited connectors) to balance value hands (e.g., big pairs, big high cards).
3. Facing the BTN: The BTN has positional advantage and can 3-bet or call CO's raise. Therefore, CO's range needs to be strong enough to avoid frequent exploitation by the BTN. Typically, CO folds hands that are easily dominated (e.g., K2s, Q5s).

Adjustment Factors

• Stack Depth: With deep stacks (100BB+), increase the proportion of speculative hands (e.g., suited connectors, small pairs); with shallow stacks (40BB or less), focus on high cards and value hands.
• Blind Players: If SB/BB have high call frequencies, tighten the range and increase value hands; if they fold often, loosen the range to about 30% of hands.
• BTN Tendencies: If the BTN is loose-aggressive and 3-bets frequently, tighten the range and add more 4-bet bluffs; if the BTN is passive, loosen the range and steal blinds often.
• Previous Limpers: If someone limps in front, adjust the range: either raise to isolate or fold. Generally, it's not recommended for CO to call a limp unless there is a special read.

GTO Reference

From a GTO perspective, the optimal CO opening range depends on the blinds and BTN's actions. Generally, CO raises 2.5-3BB with a range of about 22%-25% of hands. Hand selection should follow "exploitative balance": increase bluffs against blinds that fold often, and increase hands with nut potential against blinds that call often. Modern solvers suggest a CO range that includes: all pairs, most suited aces, some suited connectors (54s+), and high cards (A9o+, KTo+, QJo+).

Practical Application

• Standard Raise: In most cases, CO raises 2.5BB with the recommended range. If the blinds are particularly tight, a 2BB raise can be used to reduce risk.
• Facing a 3-Bet: When BTN or blinds 3-bet, fold weak hands (e.g., low suited connectors), 4-bet with strong hands (QQ+, AK), and call with medium-strength hands (TT, AQ).
• Blind Stealing Strategy: When the blinds have a high fold rate, use the bottom of the range (e.g., 64s, J7s) to raise, increasing stealing frequency.
• Postflop Play: Due to positional advantage, CO can use the range advantage to continuation bet (c-bet) on the flop, but be careful not to over-bluff.

In summary, the CO opening range is key to balancing value and bluffs. Adjust flexibly based on opponent dynamics to maximize long-term profit.