Basic strategy
Blackjack 11 vs Ace: Should You Hit or Double Down?
Hard 11 against a dealer Ace is a rule-dependent blackjack decision. Learn when basic strategy says to double, when to hit, and why H17, S17, and hole-card rules matter.
Guides
Learn the play, then drill it.
Strategy, table rules, and Hi-Lo — written to match how TwentyOne trains decisions.
Basic strategy
Blackjack Dealer Bust Odds by Upcard: Full Chart
Dealer bust odds change dramatically with the upcard. See the probabilities for every dealer card and learn how they explain—but do not replace—basic strategy.
Basic strategy
Blackjack 16 vs 10: Should You Hit, Stand, or Surrender?
Hard 16 against a dealer 10 is one of blackjack’s closest and most uncomfortable decisions. Learn when to surrender, when to hit, and why some multi-card 16s can stand.
Table rules
What Is a Push in Blackjack? Tie Rules Explained
A push in blackjack means you and the dealer tie, so the wager is returned with no profit or loss. Learn the important exceptions involving blackjack, 21, busts, splits, and doubles.
Basic strategy
Blackjack 12 vs 3: Should You Hit or Stand?
Basic strategy says to hit a hard 12 against a dealer 3. Here’s why that uncomfortable play is correct, when 12 should stand instead, and the exceptions worth knowing.
Table rules
Resplitting Aces in Blackjack: What RSA Means
RSA means resplitting aces after a split hand receives another ace. Learn how the rule works, why it helps the player, and how it differs from ordinary resplitting.
Table rules
Blackjack House Edge Explained: What Changes the Odds?
Blackjack does not have one universal house edge. Learn how payout, H17/S17, DAS, surrender, deck count, and basic strategy change the casino’s advantage.
Table rules
DAS vs NDAS in Blackjack: How the Rule Changes Strategy
DAS lets you double down after splitting a pair; NDAS does not. That small-looking rule changes several pair decisions and modestly shifts the house edge.
Table rules
Blackjack Insurance Explained: Is It Ever Worth It?
Blackjack insurance pays 2:1 if the dealer has a ten-value card under an Ace. For a basic-strategy player, the math says decline it—including even money.
Card counting
Running Count vs True Count in Blackjack: Explained
The running count tracks Hi-Lo tags as cards are exposed. The true count adjusts that number for decks remaining, making the same count comparable at different points in the shoe.
Basic strategy
When to Surrender in Blackjack: The Basic Strategy Guide
Surrender looks like giving up, but in the right blackjack hands it saves money. Learn exactly when basic strategy says to surrender—and when it doesn’t.
Table rules
3:2 vs 6:5 Blackjack: Why the Payout Matters
A 3:2 blackjack pays $15 on a $10 bet; 6:5 pays only $12. That small-looking difference adds roughly 1.4 percentage points to the house edge, all else equal.