Blackjack rules and house edge

Blackjack is a house-banked card game. The usual goal is to have a hand total closer to 21 than the dealer, without going over 21. Face cards count as 10, aces count as 1 or 11, and the dealer plays to a fixed rule, commonly standing on 17.

A “blackjack,” usually an ace and a 10-value card on the first two cards, is typically paid at 3 to 2 in traditional rules. Some games pay 6 to 5 instead. That single change significantly increases the house edge and is one of the first rules to check.

Players may be allowed to hit, stand, double down, split pairs, or, in some games, surrender. The dealer does not make those choices. Because the dealer plays last and wins ties on a bust only when the player has already busted, and because of the pay table, the game is designed to keep a long-run edge for the house.

The exact house edge depends on the rules: number of decks, whether the dealer hits or stands on soft 17, whether doubling after a split is allowed, whether doubling is limited to certain totals, whether late surrender is offered, and whether blackjack pays 3:2 or 6:5. With common, relatively player-friendly rules and mathematically correct basic strategy, the house edge is typically well under 1 percent, and is often cited around one-half of 1 percent. We do not quote a single universal number because a different pack of rules produces a different figure.

Basic strategy is a chart of the statistically better play for each player hand against each dealer up-card, assuming published rules. It is not a system for beating the game. It only avoids the extra edge that comes from common playing errors. Card counting, where it is even theoretically relevant, is a separate, difficult technique used in some live games; online and continuous-shuffle games are not designed to make that practical, and casinos may refuse play they consider advantage play. This site does not teach counting.

If you see side bets — such as insurance, perfect pairs, or 21+3 — treat them as separate wagers with their own, usually much higher, house edges. Insurance is generally a poor bet unless you are engaged in counting in a live game, which most players are not.

Online, only use a blackjack game at a site licensed in a U.S. state that has authorized internet gaming, and only when you are physically in that state. See the state legality guide.

What to look at on a rules card

• Blackjack payout: 3:2 is the traditional standard; 6:5 is worse for the player.
• Dealer action on soft 17: standing is generally better for the player than hitting.
• Number of decks and whether doubling or surrender is allowed.
• Whether any side bets are presented as if they were part of the main game.

See also: all game guides, where online casinos are legal, and responsible gambling help.