Cutoff CO Opening Range Guide: From Basics to Advanced

Why the Cutoff Is So Important

The Cutoff (CO) is the position to the right of the dealer. On the flop, the CO always acts last (unless the dealer is in the hand), giving it a huge informational advantage and opportunities to steal blinds. In a standard six‑handed game, the CO is the third player to enter the pot, with UTG and HJ (HiJack) in front, and the button, small blind, and big blind behind. Because the button defends a very wide range, the CO’s opening strategy must balance value and balance.

Standard Cutoff Opening Range

Below is a benchmark CO range for most six‑handed cash games (100bb deep). Note: you should adjust based on opponents and dynamics in actual play.

Suggested Six‑Handed CO Opening Range (About 25%–30% of Hands)

• Strong hands (3‑bet or open): AA, KK, QQ, AKs, AKo, AQs, AQo, etc. These are usually opened for a raise; if someone raises before you, consider 3‑betting.
• Medium‑strength hands (open for a raise): TT, 99, 88, 77, A10s, KJs, KQo, QJs, J10s, 109s, etc. These have enough equity from the CO and can leverage position.
• Speculative hands (open or call): 44–66, A9s–A2s, K9s, Q9s, J9s, 109s, 98s, 87s, etc. These benefit from multi‑way pots or blind stealing, but should not be used too frequently.

Example combination breakdown (about 280 combos, reduced to ~250 after trimming marginal hands):

• All pairs: 22+ (about 78 combos) – The worst pairs (22–33) are opened less often from the CO, usually only when defending from the small blind.
• All aces: A2s+, A9o+ (about 80 combos) – A2s–A5s are good for stealing; A9o and above can be opened.
• Suited connectors and gappers: 54s+, 86s+, T9s+, Q9s+, J9s+ (about 36 combos) – These have good post‑flop playability.
• Some high cards: KTo+, QTo+, JTo (about 36 combos) – Avoid too many junk hands.

Total opening frequency: about 25%–28%. If opponents fold often, you can widen to over 30%; if the button 3‑bets frequently, tighten up.

Full‑Ring (9 or 10 Players) Adjustments

In a full‑ring game, with more players ahead, the CO should tighten by about 5%. Suggested range:

• All pairs (66+; 22–55 can be opened if the table is folding a lot)
• All suited aces (A2s+)
• All ace‑high hands (AJo+)
• Suited connectors (T9s+; 98s only if the button is very weak)
• High cards (KQo, KJo, QJo)

Frequency: about 18%–22%.

Adjusting the Open‑Raise Size

The standard CO open‑raise is 2.5bb (2.5 times the big blind). But you should adjust based on the blind players:

• If both blinds are tight (fold often): raise to 2bb to reduce risk and make stealing more profitable.
• If one of the blinds is loose (calls or 3‑bets a lot): raise to 3bb or even 3.5bb to squeeze their calling range and reduce their EV of calling with junk.
• If the big blind is an aggressive 3‑better: consider raising to 2.2bb and folding to a 3‑bet, or increase your 4‑bet bluffing frequency.

Strategies Against Different Opponents

When the Button Is Very Tight (High Fold Rate)

The CO can widen its opening range significantly, including low pairs (44–66), small suited connectors (76s), and weak aces (A9o). Also reduce the raise size to 2bb because stealing is cheaper. Suggested opening frequency can reach 35% or more.

When the Button Is Very Loose (Calls or 3‑Bets a Lot)

Tighten your range, opening only value hands and hands you can 3‑bet (small pairs as traps). Increase raise size to 3bb, and be ready to fold or 4‑bet (depending on your hand) when facing a 3‑bet. Reduce the use of marginal speculative hands.

Against Aggressive 3‑Bettors

If the button or big blind frequently 3‑bets, the CO should reduce its opening frequency and adjust its range for calling 3‑bets:

• Strong hands (QQ+, AK): 4‑bet or call.
• Medium hands (TT–JJ, AQ): call.
• Other hands (e.g., AJo, KQo): fold.

At the same time, you can increase your 4‑bet bluff frequency, using hands like A5s, K9s, etc., but keep it under 1/3 of the time.

Common Mistakes and Corrections

• Opening too wide: In a full‑ring or tight game, opening over 35% from the CO will often get you exploited by button defenders. Use a HUD to monitor your CO open frequency and keep it between 20%–30%.
• Using the same raise size every time: Always 2.5bb makes you predictable. Adjust based on the blind players’ tendencies.
• Ignoring the style of players behind you: The button’s looseness directly affects your steal success. When the button is tight, even with a trash hand like 82o, it’s not recommended to open – although you might steal the blinds, you’ll have a hard time winning a big pot post‑flop.
• Overlooking the big blind’s defense ability: The big blind is the easiest position to call from preflop. If the big blind is a calling station, the CO should open more value hands and fewer speculative ones.

Advanced: Range Balance and Frequency

Advanced players mix different sizes and frequencies in the CO. For example, sometimes opening AA to 2.2bb (balanced steal), other times opening 87s to 3bb (polarized range). However, most players are better off mastering a fixed range first before gradually mixing. A simple balancing approach: maintain a ratio of value hands to bluffs of about 2:1 (e.g., in your opening range, for every two value hands, include one bluff hand).

Remember, the CO is a good position postflop, but incorrect preflop choices can lead to direct exploitation. Practice daily choosing to open or fold in the CO, and develop the habit of adjusting based on opponents.