Cutoff Opening Range Guide: From GTO to Exploitative Strategies

What is the Cutoff (CO)?

The cutoff (CO) is the position immediately to the right of the button and the third position after the under-the-gun (UTG) seats. Since the CO is the last actively acting position preflop (unless the button calls or raises), it enjoys a significant informational advantage: you can observe the actions of all UTG and middle position players, while only the button, small blind, and big blind remain to act behind you. Consequently, the CO’s opening range is wider than earlier positions, but you still need to account for the button’s squeeze and the blinds’ defense.

Standard CO Open-Raising Range (100BB Effective Stacks)

Assuming a 6-max table, with no ante or a standard ante, and an open-raise of approximately 2.5BB. A balanced GTO range comprises roughly 25-30% of all starting hands. Below is a classic range example (about 28%):

• Strong hands (value raises): All pairs (22+), all A-high cards (A9s+, ATo+), all suited connectors (T9s+), plus some medium-strong suited connectors (86s+) and suited one-gappers (J8s+, Q9s+, K9s+).
• Medium hands: Some suited aces (A2s-A8s), some weak suited connectors (54s-76s), and a few offsuit high cards (KTo, QTo, JTo).
• Bluffs/balance hands: A few offsuit weak cards like T9o, 98o, but suited hands are generally preferred.

Typical Range List (Approximate):

• All pairs 22+ (including 22)
• All suited aces (A2s+)
• All offsuit aces (A9o+)
• All suited kings (K2s+? Actually K9s+ is more standard, but some K7s-K8s could be included)
• All offsuit kings (KTo+)
• All suited queens (Q9s+)
• All suited jacks (J8s+)
• All suited tens (T8s+)
• All suited nines (98s, 97s)
• Some suited eights (87s, 86s)
• Some suited sevens (76s)
• Some suited sixes (65s)
• Occasionally add A5o, A4o for balance

Note: The actual range should be adjusted dynamically based on position. For example, tighten the range if the button is very aggressive; widen it if the blinds are very loose.

Adjustments for Different Opponent Types

Against a Tight-Passive Button

• The button calls or 3-bets infrequently, so you can open more often (expand the range to about 30-35%) and continuation-bet more heavily.
• Add more suited connectors and weak A-high hands to steal blinds profitably.

Against an Aggressive Button

• The button 3-bets frequently, so you need to tighten your opening range (approximately 22-25%), keeping mostly strong hands to avoid trouble when re-raised.
• Consider frequent 4-bets or folds, reducing medium-strength hands.

Against Weak Blind Defense

• If the small and big blinds fold frequently postflop, you can greatly expand your range (35%+), especially stealing pots in position.
• Example: all pairs, all A-highs, all suited connectors, all suited one-gappers, even some KTo, QJo.

Against Tight-Passive Blind Defense

• The range can be moderate (28%), but pay attention to continuation-bet frequency.
• If opponents often fold postflop, use smaller bets more often.

Strategy for Different Stack Depths

Short Stack (30-50BB)

• The range should be tighter (about 20-25%), primarily value raises.
• Avoid weak suited connectors and one-gappers, as they are hard to realize equity postflop.
• Increase raise size (3-4BB) to reduce opponents’ pot odds.
• Aggressively push or call all-ins with strong pairs and A-high hands.

Medium Stack (60-100BB)

• Standard range (28%), with some balance.
• Raise size around 2.5BB, staying flexible.
• Use position to c-bet often postflop.

Deep Stack (150BB+)

• The range can be expanded (30-35%), adding more suited connectors and speculative hands.
• Raise size standard or slightly smaller (2-2.5BB) to control the pot.
• Be cautious postflop to avoid being outdrawn in large pots.
• Frequently execute complex 3-bets and 4-bets.

Key Postflop Strategy Points

1. Continuation Bet Frequency: The CO hits a top-tier made hand on the flop about 1/3 of the time, but on dry boards, even without a hit, a c-bet can be made about 50-60% of the time.
2. Check Range: When you miss the flop, mainly check to take a free card.
3. Facing a Check-Raise: In most cases, fold unless you have a draw or a strong hand.
4. Value Betting: When you have a strong made hand (two pair or better), consider a large bet or all-in.

Common Mistakes

• Over-raising weak hands when the button is deep: Easily exploited by the button’s 3-bet bluffs.
• Ignoring opponents’ 3-bet tendencies: Use HUD data to adjust your range.
• Over-c-betting postflop: Especially on dry boards, this can lead to calls or raises.

Summary

The cutoff opening range should be flexibly adjusted based on opponents and stack depth, using GTO as a foundation. The general principle is: tighten against an aggressive button, loosen against a passive one; tighten with short stacks, loosen with deep stacks. Remember, position is poker’s biggest advantage—using the CO position effectively can significantly boost your win rate.