What is Double down?
Double down is a blackjack option allowing a player to double their original bet after the first two cards in exchange for receiving exactly one more card.
Doubling is most useful when the player's total is strong and the dealer's upcard is weak. A classic example is a hard 11 against a dealer 6: a £10 bet becomes £20, and one card is drawn. Basic strategy identifies the hands where doubling increases the player's expected value.
House rules vary. Some casinos allow doubling on any two cards, others only on totals of 9, 10 or 11. Whether a player may double after splitting a pair also affects the house edge, and allowing it slightly favours the player.
Restrictions on doubling are one of several small rule changes that together determine how much a blackjack table costs to play. Online and live dealer tables state their doubling rules in the game information screen, and those rules feed directly into the calculated house edge for each table.
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