Blackjack

Blackjack (also called 21) is the most-played casino card game in the world — and the casino game with the lowest house edge (~0.5%) when played with basic strategy. The objective is simple: beat the dealer’s hand without going over 21. The depth comes from when to hit, stand, double, or split — decisions that, with optimal play, turn blackjack into the most player-favorable casino game ever offered.

How to play

• Card values: 2-10 face value; J, Q, K = 10; A = 11, or 1 if 11 would bust you (the game counts it for you).
• You and the dealer get 2 cards each. Your two cards face-up; dealer’s first card face-up, second face-down.
• Hit = take another card. Stand = keep your hand. Double = double your bet, take exactly one more card. Split = if your two cards are a pair, split into two hands.
• Bust = total exceeds 21. You lose immediately, regardless of what the dealer does later.
• Dealer rule: dealer must hit on 16 or less, stand on 17 or more. In this game the dealer stands on all 17s, including soft 17 (A+6); some casinos have the dealer hit soft 17.
• Blackjack: Ace + 10-value card on initial deal = natural blackjack. Usually pays 3:2 (some casinos pay 6:5 — avoid those).
• Whoever is closer to 21 without going over wins. Equal totals are a push (your bet comes back).
• This table: 4-deck shoe, blackjack pays 3:2, double on any first two cards (including after a split), split any two cards of equal value up to four hands, and split Aces can be hit. The dealer checks for blackjack right after the deal: a dealer blackjack wins at once unless you also have one (push). An Ace and a 10 after a split counts as 21, not blackjack, and pays 1:1. There is no insurance or surrender.
• Chips: you start with 1,000 practice chips, bet with the 5/25/100/500/1000 chips, and your stack and best total are saved in your browser. Go broke and the stack refills to 1,000.

Basic strategy (the most important table in gambling)

Basic strategy is the mathematically-optimal action for every possible (your hand, dealer’s up-card) combination. It was computed in the 1950s by Roger Baldwin and refined later. Following basic strategy reduces house edge from ~2% to ~0.5%.

• Hard totals:
  • 5-8 → always hit
  • 9 → double vs dealer 3-6, else hit
  • 10 → double vs dealer 2-9, else hit
  • 11 → double vs dealer 2-10; vs an Ace, double or hit depending on the rules
  • 12 → stand vs 4-6, hit vs 2-3, hit vs 7-A
  • 13-16 → stand vs 2-6, hit vs 7-A
  • 17+ → always stand
• Soft totals (hand with an Ace):
  • A,2 or A,3 → double vs dealer 5-6, else hit
  • A,4 or A,5 → double vs dealer 4-6, else hit
  • A,6 → double vs 3-6, else hit
  • A,7 → stand vs 2,7,8; double vs 3-6; hit vs 9,10,A
  • A,8 or A,9 → always stand
• Pairs:
  • A,A → always split
  • 8,8 → always split
  • 2,2 / 3,3 / 7,7 → split vs dealer 2-7
  • 4,4 → split vs dealer 5-6 (or never if doubling after split not allowed)
  • 5,5 → never split, double down instead
  • 6,6 → split vs 2-6
  • 9,9 → split vs 2-9 except 7 (hands of 18 beat 7s well)
  • 10,10 → never split (20 is great)

Beginner strategy (the easy version)

• The “17 rule”: stand on 17+, hit below 17. Loses ~1% extra to the house but easy to remember.
• Always split Aces and 8s. Two of the most profitable splits.
• Never split 10s or 5s. 20 is a near-winning total; 5,5 is a 10, perfect to double.
• Never take insurance. Insurance is a side bet on the dealer’s Ace becoming blackjack. It has a 5-7% house edge — worse than the main game.
• Don’t follow other players’ hits/stands. Your decision should be based on your hand and the dealer’s up-card, never on what others do.

Advanced strategy: card counting

• The concept: as cards are dealt, the remaining deck composition changes. When more high cards (10s, face cards, Aces) remain, the player has an edge. When low cards remain, the dealer has the edge.
• Hi-Lo count: +1 for 2-6, 0 for 7-9, -1 for 10-A. Running count divided by remaining decks = “true count.” Bet more when true count is positive.
• Card counting is legal, but casinos may ban counters. Counting flips the house edge — turning blackjack into a small positive expected-value game (+0.5% to +1.5% for the player).
• Counting in modern casinos is harder. Six- and eight-deck shoes with deep cut cards limit the swing. Continuous shuffle machines eliminate counting entirely.
• Don’t try counting in a real casino without practice. Variance is high. Even with a +1.5% edge, you can lose for hours.

Blackjack history

• 1700s — Vingt-et-Un (France): Twenty-One in French casinos. Spreads through Europe and North America.
• 1931 — Nevada legalization: Nevada legalizes casino gambling and blackjack becomes a Vegas staple. The “blackjack” name comes from an early bonus payout for an Ace of spades and a black jack.
• 1956 — Baldwin et al.: Four U.S. Army mathematicians publish “The Optimum Strategy in Blackjack” — first basic strategy computation.
• 1962 — Beat the Dealer: Edward O. Thorp publishes his card-counting system. Casinos modify rules (more decks, dealer hits soft 17) to counter it.
• 1980s — MIT Blackjack Team: a group of MIT students reportedly wins millions using team-based counting. Later dramatized in books and movies (21).
• 2000s — televised tournaments: events such as the World Series of Blackjack turn tournament-format blackjack into a TV spectacle.

Common mistakes

• Standing on hard 12 vs dealer 2-3. Beginners stand fearing the bust. Math says hit (13-16 vs 2-3 is a stand).
• Hitting on hard 17. 17 is borderline, but the dealer must hit 16 or below — let them bust.
• Taking insurance. Always a sucker bet.
• Doubling on bad hands. Doubling on hard 12 when the dealer shows 5 is not basic strategy — it’s gambling.
• Splitting 10s. 20 wins the large majority of hands. Don’t break it up.

Blackjack variants

• European Blackjack: dealer doesn’t get hole card until after player decides. Slightly different strategy.
• Spanish 21: the 10-spot cards are removed from the deck (face cards stay). Different basic strategy. Bonus payouts for specific hands.
• Pontoon (British/Australian): different terminology (twist, stick, buy), 5-card trick beats 21.
• Double Exposure: both dealer cards face-up. Sounds player-friendly, but the dealer wins ties and blackjack usually pays only even money.
• Blackjack Switch: play two hands; swap second cards between hands. Player-favorable rules with twists.

FAQ

• Q: Why doesn’t this game cost me money? A: This is a single-player practice mode with virtual chips. No real wagering.
• Q: What’s the lowest house edge in casino blackjack? A: Around 0.5% in typical multi-deck games with perfect basic strategy. Rare single-deck games with a 3:2 payout, dealer standing on soft 17 and doubling after a split allowed come close to 0%.
• Q: Should I always hit on 16? A: Hit on 16 vs dealer 7-A. Stand on 16 vs dealer 2-6.
• Q: Why is splitting Aces always right? A: Two hands starting with Ace each give two chances at 21. Most casinos restrict you to one card per split Ace (no further hits), but the expected return still beats playing A,A as 12. This table lets you keep hitting split Aces.

For other casino-style games, try Video Poker, Roulette, Slot Machine, or Yahtzee.