KEPU Article: AA vs 55 at 100BB Strategy

I. Definition and Background

In Texas Hold'em, pocket Aces (AA) is the strongest starting hand, while pocket Fives (55) is a typical small-to-medium pair. When effective stacks are 100 big blinds (BB), preflop all-in or calling decisions are critical. This article assumes a standard six-max table, both players are rational, and there is no postflop play (i.e., everything is decided preflop).

II. Win Rate Principle

According to poker probability, AA has about 80% equity against 55 preflop all-in. This is because AA, as an overpair, is only outdrawn by 55 hitting a set about 20% of the time. Breakdown:

• AA equity: ~80% (including times when 55 misses a set and AA stays ahead, plus rare cases where AA outdraws a set via a straight or flush).
• 55 equity: ~20% (mostly by flopping a set, or via straight, flush, or race scenarios at low probability).

Note that this equity is based on all-in preflop and running five community cards. If postflop play is possible (e.g., a pot-sized bet forcing a fold), the situation becomes more complex.

III. Preflop Strategy at 100BB

1. When Holding AA

• Preflop Raise and 3-bet: As the AA holder, you should typically raise or 3-bet preflop to build the pot and narrow the range. Standard sizing: 3-4 BB against one raiser, or 4-5 BB against two or more.
• Facing a Re-raise: If the opponent (holding 55) re-raises to 20-40 BB, AA should either go all-in or 4-bet to an acceptable size. At 100BB, an AA all-in is almost always +EV. However, if the opponent is tight-passive and only re-raises with AA/KK, AA all-in is still profitable but requires awareness of reverse implied odds.
• All-in Decision: Open-shoving 100BB is usually not optimal as it drives out weaker hands. But if the opponent’s range includes many small-to-medium pairs (e.g., 55-99), an all-in can immediately win the pot.

2. When Holding 55

• Preflop Call or Fold to 3-bet: 55 is suitable for calling in multi-way pots to see a flop for a set. If facing a raise, the implied odds require sufficient stack depth for both the raiser and callers. Typically, you need at least 15-20 times the call amount in effective stacks to profit. For example, facing a 3 BB raise at 100BB, you need about 40-60 BB in implied odds, and the probability of flopping a set is ~12%, making the call marginally +EV.
• Facing an All-in: If the opponent shoves 100BB, 55 has only 20% equity. You’d need to pay 80-100 BB to compete for a pot of ~200 BB. Expected value: 0.2 * 200 - 0.8 * 100 = 40 - 80 = -40 BB. Therefore, unless the opponent is shoving extremely wide (e.g., two overcards), 55 should fold.
• As a Re-raiser: If you re-raise with 55, you usually hope for a fold. If called, postflop will be tough since most flops miss your set. In deep stacks, if your re-raise is met with a 4-bet, you should fold.

3. Preflop Game Theory Equilibrium

In GTO strategy, AA almost always raises or 4-bets preflop, while 55 does not voluntarily shove 100BB unless the opponent folds too often. In practice, consider opponent types: loose-passive players may call too much with 55, while tight-aggressive players are more likely to fold.

IV. Practical Examples

Example 1: Standard Open

• Blinds 0.5/1, effective stack 100 BB.
• UTG raises to 3 BB, button calls, you are in the big blind with AA. You should: 3-bet to around 12 BB, or shove (not preferred). Button calls 3 BB, you shove, UTG folds, button calls and shows 55. Flop K-8-2 (no 5), AA wins.

Example 2: 3-bet Confrontation

• Button raises to 3 BB, small blind 3-bets to 10 BB, big blind folds. Button holds 55, effective stack 100 BB. Button should: fold. Because the 3-bettor’s range is strong (top ~5%), 55 has insufficient equity and implied odds are ruined.

Example 3: Preflop All-in

• Preflop early position raises to 4 BB, middle position 3-bets to 15 BB, cutoff (has AA) 4-bets to 40 BB, button (has 55) shoves 100 BB. Cutoff should call, button made a mistake. After button’s all-in, cutoff calls, AA has 80% equity.

V. Common Mistakes

1. “AA is always the best hand to shove preflop”: True, but the shove size should be adjusted based on opponent fold equity. Over-shoving allows opponents to fold hands that could bluff, reducing profit.
2. “55 should always call a raise to see a flop”: Incorrect. If the raise is too large (over 5 BB) or effective stacks are shallow (<100 BB), calling is -EV.
3. “Shoving 100 BB with 55 is OK”: Seriously wrong. Unless you confirm the opponent’s range is extremely weak (e.g., two overcards), expected loss is tens of BB.
4. “All-in preflop equity is fixed”: But AA vs 55’s 80% equity is an average; actual results vary with flush and straight board textures.

VI. Conclusion

At 100BB depth, AA should be aggressively raised/3-bet and either shoved or 4-bet when facing a re-raise. 55, as a small-medium pair, should lean toward calling to see a flop and avoid all-in confrontations with AA. Correctly balance implied odds and expected value, and avoid the “set-mining fantasy” that leads to -EV decisions. Ultimately, position and player reads matter, but basic math shows: AA is the eternal equity king, while 55 is a speculative gambler.