Detailed Guide to CO Open Range: How to Use Position Advantage to Build Profitable Range

Position Description

Cut Off (CO) is the position to the right of the Button (BTN). In a full nine-handed game, CO is in the mid-late position and gets to act last post-flop (as long as the Button, Small Blind, or Big Blind hasn't raised). Due to its late position, CO can open wider than early positions (UTG, MP) while still retaining post-flop pot control.

Recommended Range

Below is a typical GTO-oriented CO open range (assuming 100BB effective stacks, no ante, standard table dynamics). The range is roughly 23%–25% of hands and includes:

• All pairs: 22+ (approximately 6% of hands)
• All suited connectors: 54s+ (approximately 4%), plus some high suited aces like A2s+ (approximately 3%)
• All offsuit broadways: AJo+, KQo, ATo+ (approximately 6%)
• Some suited Ax: A2s–A9s (approximately 3%)
• Some suited two-broadways: KJs+, QJs+, JTs (approximately 1.5%)
• Some offsuit middle cards: KJo, QJo, JTo (approximately 2%)

Specifically, the following hands are suggested as a baseline range (approximately 23%):

• All pairs: 22–AA (12 pairs × 6 = 72 combos)
• All suited aces: A2s–A5s (4 suits × 4 = 16), A6s–A9s (4 suits × 4 = 16, but marginal and can be folded)
• All suited connectors: 54s–JTs (7 suits × 4 = 28, but excluding T9s? Actually recommended 67s+) More precisely: suited connectors from 65s to T9s (6 suits × 4 = 24)
• All offsuit broadways: ATo+ (AJo+ is 3 pairs × 12? ATo is 4 pairs × 12? Correction: AJo+ includes AJ/AQ/AK (3 pairs × 12 = 36), KQo (1 pair × 12 = 12), ATo (1 pair × 12 = 12), total 60)
• Suited two-broadways: KJs+, QJs+, JTs (3 suits × 4 = 12)

Total: Pairs 72 + suited aces (16+? Can add A2s–A5s 16) + Suited connectors 24 + Offsuit broadways 60 + Suited two-broadways 12 = 184 combos, approximately 14%? No, total hands 1326 combos, 14% is about 185 combos. But a typical CO range is about 23–25%, so more must be added. A typical CO range includes:

• All pairs 22+ (72 combos)
• All suited Ax (A2s–A9s, 8 × 4 = 32)
• All suited connectors 54s+ (T9s, 98s, 87s, 76s, 65s, 54s total 6 × 4 = 24)
• All suited one-gappers: J9s, T8s, 97s, 86s, 75s, 64s, 53s (7 × 4 = 28, but usually only part)
• All offsuit broadways: ATo+, KJo+, QJo (AT: 4 × 12 = 48? Actually ATo has 12 combos, AJo 12, AQo 12, AKo 12, KQo 12, KJo 12, QJo 12, total 72 combos)
• All suited broadways: KJs+, QJs+, JTs, T9s, etc. (KJs 4, KQs 4, QJs 4, JTs 4, T9s 4, 98s 4? Total 24 but duplicate?)

For simplicity, we describe as:

• All pairs (22+)
• All suited aces (A2s–A9s)
• All suited connectors (54s–T9s) and some suited one-gappers (e.g., J9s, T8s, 97s, 86s)
• All offsuit high cards: ATo+, KJo+, QJo
• All suited high cards: KJs+, QJs+, JTs, T9s

Approximately 300+ hand combos, about 23%–25%.

Range Construction Logic

CO range construction is based on two core factors: positional advantage and squeeze risk from behind.

Positional advantage: Post-flop, CO can control the pot more precisely than early positions, especially when the blinds don't raise. Therefore, more speculative hands (small pairs, suited connectors) and marginal value hands (weak Ax) can be added.

Squeeze risk: If CO limps, the Button or blinds might squeeze-raise. Therefore, CO usually prefers to open raise rather than limp. Recommended open raise size is 2.5–3BB (standard 100BB).

Adjustment Factors

• Opponent style: If blinds frequently 3bet, tighten the range, removing some weak suited connectors and one-gappers, while increasing the 4bet bluff range. If blinds are too passive, the range can be widened.
• Stack depth: Deep stacks (150BB+) allow more small pairs (for set mining) and suited connectors; shallow stacks (30–50BB) should reduce speculative hands and focus on value.
• Ante structure: With ante, the pot is larger, so the range can be slightly widened, but not excessively.
• Button position: If the Button is a loose-aggressive player, consider tightening the range to avoid being squeezed.

GTO Reference

According to simulation results from modern GTO software (such as PokerSnowie, GTO Wizard), the GTO open-raise range for CO in a 100BB no-ante scenario is approximately 23%-25%, with a raise frequency of about 23%. Specific hand weights:

• High pairs (TT+) and AK: nearly 100% raise.
• Medium pairs (77-99): about 80-90% raise.
• Small pairs (22-66): about 60-70% raise, fold the rest.
• Suited connectors (65s-T9s): about 70-80% raise.
• Unsuited broadways (ATo+): about 80-90% raise.
• Suited Ax: about 70-80% raise.
• Marginal hands (e.g., K9s, Q9s, J8s): about 20-40% raise, mixed with folds.

In real games, you don't need to follow this precisely, but it can serve as a baseline.

Practical Application

Typical scenario: At a nine-handed table, CO holds KTs, effective stack 100BB, no antes, blinds unknown. According to the baseline range, KTs is in the raise range (suited two high cards). Recommended raise to 3BB. If the button folds and a blind calls, make post-flop decisions based on board structure and opponent range.

Adjustment example: If the blinds are tight-aggressive with a high 3-bet frequency, fold 66 and T9s to avoid being forced into a passive position after a 3-bet.

Exploitative adjustments: If the blinds call too loose, increase your value range (e.g., KJs, ATo) and reduce your bluffing range; if the blinds fold a lot, increase your stealing range (any two cards).

Conclusion: CO is a key position for profitability. A proper open-raise range maximizes positional advantage. Remember, the range should adjust dynamically, not remain static.