Heads-Up Poker Preflop Strategy: GTO Ranges for HU Cash Games
Quick answer: In heads-up poker, the small blind (button) opens roughly 90-100% of hands and the big blind defends over 60% of its range across calls and 3-bets. Those numbers shock players coming from 6-max, but GTO solvers are clear: the two-player dynamic changes everything about preflop range construction. This guide covers the exact GTO ranges, sizing rules, and adjustments for heads-up cash games and sit-and-gos.
HU vs 6-max vs 9-max: range widths at a glance
The first thing to understand about heads-up poker is how dramatically range widths shift compared to full-ring formats. A hand that folds from UTG at a 9-max table becomes a standard open from the small blind in heads-up. The pot odds and positional edge scale completely differently with only two players.
| Metric | Heads-Up | 6-Max | 9-Max |
|---|---|---|---|
| SB/BTN opening range | 90-100% | 45-50% | 43-47% |
| BB defense frequency | 62-70% | 50-60% | 45-55% |
| BB 3-bet frequency | 15-20% | 8-12% | 6-9% |
| Standard open size | 2-2.5x | 2.5x | 2.5-3x |
| Playable hands from worst seat | All (SB = BTN) | UTG opens ~15% | UTG opens ~13% |
| Limp frequency (SB) | 25-40% of opens | Rare (exploitable) | Rare |
Sources: GTO solver outputs for 100bb NL cash games. HU figures represent mixed strategies averaged across solver runs.
Train HU ranges on your phone. Preflop Wizard includes heads-up preflop training for cash games and sit-and-gos.
The heads-up dynamic: why ranges flip
In heads-up poker, the small blind acts first preflop and last postflop. This position advantage changes the math entirely. With only one opponent, the small blind wins the pot uncontested roughly 30-35% of the time when it raises and the BB folds. That equity share drives the SB’s range to extremes: raising nearly everything is more profitable than giving up position by folding.
The BB, meanwhile, faces a 2x pot-size call to stay in a hand where it will be out of position for every remaining street. What keeps BB defense frequencies high is that the big blind already has money invested: calling 1 more big blind to win 3 (the open plus the blinds) requires roughly 25% equity, and almost every hand in a heads-up deck clears that bar against a range that wide.
Understanding this dynamic is the foundation of solid heads-up preflop strategy. The GTO framework for heads-up play is not “play tight and wait for good hands” — it is “attack constantly and defend enough that folding becomes unprofitable.”
Small blind preflop strategy in heads-up poker
The SB in heads-up poker is simultaneously the button, the dealer, and the small blind. It acts last postflop on every street, which gives it enormous positional leverage. GTO solvers respond to this by constructing a SB range of 90-100% of hands at 100bb effective.
Opening and limping ranges
A common mistake is assuming the SB should raise 100% of its hands. Modern GTO solutions actually include a mixed limping strategy from the small blind, particularly at 100bb and deeper. Roughly 25-40% of the SB’s range limps in solver solutions, typically including hands that want to see a cheap flop (medium suited connectors, small pairs) and some strong hands balanced in to prevent the BB from attacking limps aggressively.
Pure raises (2-2.5x)
Strong broadways (AK, AQ, KQ, JJ+), strong aces (A9s+), good kings (KTs+), premium suited connectors (87s-JTs)
Raise frequently for value and to build pots in position
Mixed raises and limps
Medium suited connectors (65s-76s), weak aces (A2s-A5s), medium pairs (55-99), suited kings (K2s-K9s)
Solver mixes these at various frequencies — simplify by choosing one action and applying it consistently
Pure limps
Some weak offsuit hands (Q7o, J6o), very bottom of range
Limping some weak hands balances the limp range against BB aggression
Sizing in heads-up
GTO solvers recommend smaller open sizes heads-up than full-ring formats: typically 2-2.5x rather than 3x. The reason is positional: you will always have position postflop, so you need less leverage to take the pot. Smaller raises let you enter more pots profitably with your wide range without risking too much on weak holdings.
Big blind preflop strategy in heads-up poker
The BB in heads-up sits out of position for all postflop streets, but it gets pot odds that force wide defense. Against a 2x open, the BB needs 25% equity to break even on a call. Against a 2.5x open, it needs about 29%. Nearly every holding in a two-player game clears that bar — which is why BB folding frequencies in heads-up GTO solutions are extremely low.
BB calling range vs. 3-betting range
The BB does not simply call everything. It splits its defense between calls (hands that play well out of position in small pots) and 3-bets (hands that want to build equity and occasionally take the pot pre). A typical split against a 2.5x SB open:
| Action | Frequency | Hand types |
|---|---|---|
| 3-bet for value | ~8-10% | AA, KK, QQ, JJ (mixed), AK, AQs — hands that want a bigger pot |
| 3-bet bluff | ~8-12% | Suited aces (A2s-A5s block nut holdings), suited broadways with blockers (KJs, QJs), some suited connectors |
| Call | ~40-50% | Pairs (22-TT mixed), suited connectors, suited aces (A6s-A9s), offsuit broadways, weak aces — hands that realize equity well in position vs. a capped range postflop |
| Fold | ~30-35% | Weakest offsuit non-connected hands (72o, 83o, J4o) — though even these fold less often than in 6-max |
BB 3-bet sizing
3-bet to roughly 8-10x the open in heads-up poker (3.3x is standard in 6-max, but HU 3-bets typically run larger because the pot odds and playability out of position change). Against a 2.5bb open, a 3-bet to 9-10bb is common. The larger size forces the SB to realize it needs more equity to continue, which is the point against a wide SB range.
Drill HU ranges until they’re automatic
Preflop Wizard covers heads-up preflop training for cash games and sit-and-gos. Download and practice until every HU spot feels like muscle memory.
What changes in heads-up vs. 6-max preflop strategy
Players moving from 6-max to heads-up poker consistently make the same calibration errors. The range widths are different — but so are some of the strategic principles underneath them. Here is what actually changes:
Position advantage is permanent, not variable
In 6-max, position rotates — you’re sometimes UTG. In heads-up, the SB always has position postflop regardless of table position. This makes the SB’s equity advantage more consistent and durable, justifying the extreme range widening.
Blockers matter more for BB 3-bet construction
With only one opponent, the card removal effects from blockers are more significant. A5s from the BB reduces the SB’s value 4-betting range because you hold an ace — blocking AA, AK, and some AQ combinations the SB would 4-bet for value. This makes A2s-A5s strong 3-bet bluffs from BB in heads-up specifically.
Stack-to-pot ratios stay higher
With smaller opens (2x) and narrower pots, stack-to-pot ratios (SPR) stay elevated more often in heads-up. This means more implied-odds situations postflop, which makes speculative hands (small pairs, suited connectors) more valuable than their raw preflop equity suggests.
3-bet pots are a bigger share of HU hands
Because the BB 3-bets at 15-20% and the SB opens nearly every hand, 3-bet pots occur far more often heads-up than in 6-max. Being comfortable in 3-bet pots out of position (as BB) and in position (as SB calling the 3-bet) is a skill requirement for solid HU play.
5 preflop mistakes that bleed EV in heads-up poker
Most losing heads-up players share a handful of specific preflop leaks. These are the most common, with the GTO-correct adjustment for each.
Folding too much from the BB
If you fold more than 35% of your BB range against a standard 2-2.5x open, you are giving up EV. The pot odds in heads-up simply do not justify folding most hands. A tight fold frequency lets the SB print money with its entire range.
Not including a limp range from the SB
Pure raise strategies from the SB are exploitable. The BB can raise your entire limp range aggressively, and without balance you have no way to defend. Including some strong hands and some weak hands in your limp range makes the BB’s attack less profitable. Study GTO opening range construction to understand how to balance your limps and raises from the small blind.
Using 6-max sizing heads-up
Opening 3x in heads-up wastes money. A 2-2.5x size achieves the same result (stealing the blind) while risking less. The BB’s calling range is wide enough that larger sizes do not fold out significantly more hands — they just inflate the pot when you connect.
Flat-calling the SB open too often from BB instead of 3-betting
A wide BB 3-betting range is not optional — it’s what prevents the SB from open-raising every hand for free. Without a healthy 3-bet frequency (15-20%), you let the SB realize its positional edge cheaply in every pot.
Playing the same range regardless of SB sizing
If the SB opens to 3x instead of 2x, your BB calling range should tighten and your 3-bet range should expand (to take the initiative). The math changes: a 3x open requires 30% equity to call, which cuts into the weakest parts of your flat-calling range. Adjust frequencies based on the actual size you face.
Heads-up preflop in sit-and-gos and tournaments
Heads-up situations at a tournament final table or at the end of a HU SNG follow similar principles to cash games, but stack depth changes everything. The adjustments are dramatic as stacks get short:
| Effective stack | SB strategy | BB strategy |
|---|---|---|
| 100bb+ | Open 90-100%, mix limps on 25-40% of range | Call wide, 3-bet 15-20%, fold ~30% of weakest holdings |
| 40-100bb | Open 90-100%, limping less valuable with shorter SPR | Defend similarly wide; 3-bet shoves become more relevant |
| 20-40bb | Open-raise or 3-bet jam; limp-call strategy shrinks | Calling and 3-bet shoving dominate; flat calls fewer |
| Under 20bb | Pure push/fold: jam or fold from SB | Pure call/fold based on pot odds and hand equity |
For push/fold strategy at short stacks, see our short-stack poker strategy guide and ICM strategy guide for final-table adjustments.
How to study and practice heads-up preflop ranges
Heads-up preflop is the format where drilling pays off fastest. The ranges are wide, which means there are more unique spots to internalize — but the format itself is simpler than 6-max because there are only two players and two positions. A few ways to build your HU preflop game:
Use a preflop trainer for SB and BB separately
Train your SB open range until it is automatic, then shift to BB defense. Separating the two roles makes the pattern recognition clearer — you are not mixing two very different frequency sets in the same session.
Study 3-bet pots specifically
Since HU generates 3-bet pots at 3-4x the rate of 6-max, your response to a 3-bet as SB and your 3-bet-pot play as BB from the small blind deserve specific study time. Knowing your flat-calling and 4-bet ranges in those spots is a major edge over players who never practice them.
Start with simplified ranges, then refine
The cleanest approach: raise 100% from SB (no limping) and defend 65% from BB for a few sessions, then add the limp-raise and 3-bet nuances once your base frequencies are automatic. The simplified version loses a fraction of EV but is much easier to execute consistently.
Preflop Wizard includes heads-up range training for cash games and SNGs. You can drill preflop charts for both SB and BB positions in HU format on your phone, with immediate AI feedback when you deviate from GTO. See our full guide on how to practice poker preflop ranges for the most effective study system.
Frequently asked questions
What hands should I open from the small blind in heads-up poker?
GTO solvers open roughly 90-100% of hands from the SB in heads-up at 100bb effective. In practice, this means raising almost everything, while mixing in some limps on medium-strength hands and a few strong hands for balance. If you want a simplified approach, raising 100% is closer to GTO than folding any significant chunk of your range.
How wide should I defend my big blind in heads-up?
Against a standard 2-2.5x open, you should defend roughly 62-70% of your BB range across calls and 3-bets combined. This breaks down to folding around 30-35% of the weakest offsuit non-connected hands. Anything tighter gives the SB a license to steal.
Should I limp from the small blind in heads-up?
GTO solutions include limping from the SB at 25-40% of the total SB strategy at 100bb. The logic: some hands play better in small pots (suited connectors, small pairs) and limping some strong hands prevents the BB from attacking your entire limp range with raises. A pure raise strategy works at low stakes where opponents do not exploit it, but against thinking players, adding a limp-raise and limp-call component is correct.
What hands should I 3-bet from the big blind in heads-up?
A polar 3-bet strategy works best: value 3-bets (AA, KK, QQ, AK, AQs) and 3-bet bluffs (A2s-A5s for blocking nut holdings, suited connectors with blockers, some KJs/QJs). Total 3-bet frequency in heads-up is 15-20% of your BB range against a standard 2.5x open.
How does heads-up preflop strategy change at short stack depths?
Stack depth is the biggest variable in HU preflop strategy. At 100bb, GTO solutions include limping, mixed strategies, and nuanced 3-bet sizing. At 20bb and below, the game collapses into essentially push-or-fold from the SB and call-or-fold from the BB, with only hand equity driving decisions. The transition starts around 40bb as implied odds diminish.
What is the best tool for learning heads-up preflop ranges?
A dedicated preflop trainer that covers heads-up configurations lets you drill both SB and BB positions with immediate feedback. Preflop Wizard covers HU cash game and sit-and-go preflop training on mobile, so you can practice wherever you are. For a full comparison of available tools, see our guide to GTO Wizard alternatives.