Cutoff Opening Range Explained: How to Build an Advantage in the CO Position

Detailed Guide to Cutoff Opening Range: How to Build an Advantage from the CO

The cutoff (CO) is the last non-blind position to act preflop, enjoying a significant informational advantage. Since only the Button and the blinds act after the CO, and the Button will often call or 3-bet with a wide range, the CO's opening strategy must balance value extraction and protection. This article systematically explains the logic behind constructing a CO opening range and how to adjust it in practice.

I. Basic Opening Range (Standard 100BB Deep Stack, vs Unknown Opponent)

A solid CO opening range typically includes about 22%-28% of starting hands. Below is a typical range example (100BB, 6-max, no special tendencies):

• Value Hands (Strong): All pairs (22+), all A-x high cards (A9o+, ATs+), all suited connectors (T9s+, JTs+, QTs+, KTs+), and some suited gappers (e.g., K9s, Q9s).
• Speculative Hands: Small suited connectors (54s-98s), some unsuited connectors (T9o+, JTo+), low pairs (22-66) for set-mining.
• Excluded Range: Trash hands like 27o, 82o are never opened.

A simple mnemonic for the basic range is: all pairs, all A-x hands (A2s+, A9o+), all suited connectors (54s+), some suited gappers (K9s+, Q9s+), and all J9o+, T9o+. The actual number of hand combos is about 330-350 (roughly 25% of all hands).

II. Adjustment Factors: How to Dynamically Optimize Your Range

1. Stack Depth

• Short Stack (≤40BB): Reduce speculative hands. With lower implied odds postflop, focus more on high card value and strong pairs. Tighten to about 20% of hands, removing low pairs (22-55) and small suited connectors (54s-76s).
• Deep Stack (≥200BB): Increase speculative hands. Add more suited gappers (e.g., 86s, 75s) and marginal suited connectors (43s). You can even occasionally open small pairs (22) to blind-steal, but watch for Button 3-bets. Expand to above 30% if possible.

2. Opponent Type

• Tight-Passive Blinds: You can widen your range significantly. Add more marginal hands like K9o, Q9o, J9o, and even occasionally A2o as a steal. But be careful not to get squeezed by a Button 3-bet.
• Loose-Aggressive Blinds: Tighten your range to avoid frequent 3-bets that cost you money. Cut low suited connectors and weak unsuited hands; focus on high pairs and high suited cards. If the blinds 3-bet heavily, consider 4-bet bluffing with some medium hands like AJo, KQo.

3. Button Tendencies

• Button Calls Often: This diminishes your positional advantage. Reduce pure bluff hands (e.g., 76s, 65s) because multiway pots postflop are harder to play. Add more value hands and suited connectors with nut potential.
• Button Is Tight: Expand your range to exploit the CO's stealing opportunity. Add more weak A-x hands (A8o-A2o) and suited junk (e.g., K7s).

III. Postflop Strategy Points

1. Continuation Bet Range: As the preflop raiser, you can c-bet frequently from the CO. On flops that favor your range (e.g., high cards, low boards), your c-bet frequency can exceed 70%. Avoid c-betting with pure marginal hands on dry boards (e.g., Q-7-2 rainbow), as you risk being called or raised.
2. Defending Against Blind Re-Steals: When a blind 3-bets, you need a suitable defense range. Typically 4-bet for value with AA, KK, QQ, AK, and mix in a few 4-bet bluffs like A5s, A4s. But don't over-bluff, or loose-aggressive opponents will exploit you.
3. Use Position to Play Multiple Streets: Being in position postflop allows you to see opponent actions before deciding. Use small bet sizes (1/3 pot) for thin value or bluff extensions on favorable boards.

IV. Common Mistakes and Corrections

• Opening Too Wide Preflop: Even with positional advantage, don't enter pots with a range below 20%. You'll become too vulnerable to 3-bets.
• Ignoring the Button's Presence: Don't act as if only the blinds are behind you. The Button can call or 3-bet to disrupt your steal. Always adjust to the Button's style.
• Giving Free Cards Postflop: On wet boards with draws, bet appropriately to protect your hand. Slow-playing excessively can cost you value.

V. Summary

The CO opening range is a dynamic system. Start with a base range of about 25%, then fine-tune based on stack depth, blind tendencies, and Button behavior. Understanding the adjustment logic is more important than memorizing a static range. We recommend tracking your CO performance in different scenarios to develop your intuition. Remember, the CO is your last chance preflop to seize the initiative—use it wisely to boost your win rate.