Blackjack: Rules, Odds and Strategy Guides Backed by 40 Million Simulated Hands

Blackjack is a card game you play against the dealer, not against other players. You and the dealer both start with two cards, and the goal is to finish closer to 21 than the dealer without going over. Number cards count at face value, jacks, queens and kings count 10, and an ace counts 1 or 11, whichever helps you more. An ace plus a 10-value card as your first two cards is a "blackjack", which traditionally pays 3 to 2.

What makes blackjack different from roulette or slots is that your choices matter. Every time you hit, stand, double or split, you move the house edge up or down. The rules of the table matter just as much, and some of them are easy to miss.

Blackjack odds by rule set

We simulated 10 million hands for each of four common 6-deck rule sets, 40 million hands in total, with a computer playing perfect basic strategy. Each hand was scored twice: once with blackjack paying 3:2 and once paying 6:5.

How to read it: S17 means the dealer stands on soft 17, H17 means the dealer hits it. DAS means you may double down after splitting a pair. A house edge of 0.47% means you lose about 0.47 USDT for every 100 USDT you bet, on average, over a very large number of hands.

Three takeaways:

• The payout is the biggest rule. Switching from 3:2 to 6:5 adds about 1.36 percentage points (1.827 − 0.470). No other rule in the table comes close.
• H17 and no DAS add up. The worst 3:2 game in our table (0.78%) costs you roughly 1.7 times as much as the best one.
• These are Monte Carlo estimates. Each figure has a standard error of about 0.036 percentage points. The rule-change costs published by the Wizard of Odds agree closely with the gaps in our table, all within 0.08 percentage points; the 6 to 5 blackjack guide shows the comparison.

How to use our blackjack guides

Start with the basics, then move to the numbers that save you the most money:

• 6 to 5 vs 3 to 2 blackjack: our centrepiece comparison. The same 10 million hands scored under both payouts, plus how to play blackjack from scratch.
• Blackjack strategy card: the full basic strategy chart for a 6-deck S17 game, colour-coded, with the changes you need when the dealer hits soft 17.
• What splitting means in blackjack: when to split, when not to, what happens with two aces, and what doubling after a split is worth.
• Live blackjack explained: how dealer-streamed tables work, how they differ from digital blackjack, and which rules to check before you sit down.
• Card counting resources: an honest explanation of the Hi-Lo count, why it fails in games that shuffle every hand, and where counting is legal.

Featured tool: the blackjack calculator

Charts are useful, but sometimes you just want the answer for one hand. Our calculator gives you the basic strategy move for any hand against any dealer upcard, for the rule set you're playing.

The charts behind the calculator and our strategy card follow the Wizard of Odds basic strategy for 4 to 8 decks. Our simulation then measured what that strategy actually returns under each rule set.

Blackjack with crypto and USDT

Blackjack's low edge makes each hand cheap to play, which also means small costs elsewhere stand out. Two points for crypto players:

• Fees can outweigh the edge. At 0.47%, betting 1,000 USDT in total costs about 4.70 USDT on average (1,000 × 0.47%). A single network fee on deposit or withdrawal can be a meaningful share of that. Our USDT and payments guides explain how network choice affects fees.
• A stablecoin keeps the maths clean. If your bankroll is in BTC or ETH, the coin's price can move more in an evening than the house edge does. Holding USDT means the only swings are the game's.

If you also play crypto-native games, compare blackjack's edge with the 1% built into the published crash formula in our crash gambling breakdown. A well-ruled blackjack table played with basic strategy has the lower edge; a 6:5 table does not.