Cut-Off CO Opening Range Guide: From Theory to Practice

Position Scenario Description

The Cut Off (CO) is the position immediately to the left of the button (BTN). Since only the blinds remain after the button, the CO has excellent post-flop positional advantage, but must also be wary of the button's 3-bet and the blinds' squeeze. In six-handed play, the CO is often called the "second button" and is a prime position for stealing blinds and building pots.

Recommended Range

The CO's opening range is typically wide, covering about 25%‑35% of hands. Below is a balanced, easy-to-remember example range (100BB effective stacks, no specific reads on opponents):

• All pairs: 22+ (13 total)
• All Ax: A2o+, A2s+ (but offsuit A2o-A5o are often folds depending on the situation)
• Suited connectors: 54s+ to KQs (all suited connectors, including one‑gappers like 75s, 96s, etc., but low ones like 32s are optional)
• High cards: KTo+, QTo+, JTo+ (offsuit)
• Some suited one‑gappers: J8s+, T7s+, 96s+, 85s+, 75s+ (can be widened based on positional advantage)
• Some offsuit connectors: K9o+, Q9o+, J9o+, T9o (add cautiously to avoid being dominated)

This corresponds to roughly 25.3% of starting hands (about 340 combos). In practice, you can drop the weakest combos (e.g., A2o‑A5o, K9o‑Q9o) and keep a core range of about 22%.

Range Construction Logic

1. Positional Advantage: The CO acts last post‑flop (except when the BTN is in the hand), so you can play more speculative hands (small pairs, suited connectors) and use implied odds to extract value when you hit strong hands.
2. Domination and Counter‑Domination: The CO’s raise faces 3‑bets from the BTN, so the range must include enough value hands (TT+, AQ+) to withstand 3‑bets, while mixing in some suited connectors and small pairs for defense.
3. Blind Exploitation: If the blinds defend too little, you can widen your range to steal; if they 3‑bet frequently, tighten up and add more 4‑bet hands.
4. Balance: Avoid a polarized range. Maintain a reasonable ratio of value hands to bluffs so that opponents cannot easily adjust.

Adjustment Factors

• BTN’s 3‑bet frequency: If the BTN 3‑bets often, tighten your opening range and consider 4‑bet bluffing with some hands (e.g., A5s, KQo); if the BTN is tight, you can raise more widely.
• Blind players’ style: Loose‑passive blinds invite wide stealing; tight‑aggressive blinds require caution to avoid being forced to fold to 3‑bets.
• Stack depth: In deep stacks (150BB+), increase the proportion of small pairs and suited connectors; in shallow stacks (below 40BB), focus on high cards and big pairs, reducing speculative hands.
• Opponent type: Against weak players, you can widen your range and add more marginal hands, leveraging your post‑flop skill edge; against strong players, keep a balanced range to avoid being exploited.

GTO Reference

Under a GTO (Game Theory Optimal) framework, the CO’s balanced opening range is about 29.5% of hands (with 100BB, no ante, standard open size of 2.5BB). The approximate distribution is:

• Top value (TT+, AQ+): ~6% of hands, for value betting.
• Medium strength (KJ+, QT+, pairs 77‑99): ~8%.
• Low speculative (suited connectors, small pairs, small Ax): ~15.5%.

GTO requires that every combo in the range be raised with equal frequency, and that when facing a 3‑bet, some hands (e.g., AJo, KQo) mix folds and 4‑bets. In practice, players can deviate based on opponent tendencies.

Practical Application

Example 1: Blinds are loose‑passive, BTN is tight. CO can extend the standard range (22%+) by adding all offsuit connectors (K9o, Q9o, J9o, T9o) and some low suited connectors (65s, 54s), expanding the range to about 30%. After raising, if blinds call with many hands, bet more post‑flop; if BTN enters, proceed cautiously.

Example 2: Blinds are tight‑aggressive 3‑bet regulars, BTN is also aggressive. CO should tighten to about 18%, playing only pairs 77+, AXs, AJo+, KQo+, and suited connectors preferably 78s+, and be ready to 4‑bet. For example, holding A5s, facing a BTN 3‑bet, you can 4‑bet bluff; with TT+, value 4‑bet.

Example 3: Against unknown opponents, start with a balanced ~22% range (e.g., the recommended range minus the weakest 20%). Observe a few orbits and adjust based on opponents’ defensive tendencies. If you often succeed in stealing, gradually widen; if you face multiple 3‑bets, tighten and increase your 4‑bet frequency.

Remember, position is the CO’s greatest weapon. Use it to control pot size post‑flop and make more accurate decisions. Practice often, incorporate reads and dynamics, and your CO profitability will improve significantly.