About Blackjack

Blackjack is the most well known and most popular casino game available. Even movies have been made around the game of blackjack. It has pretty simple objective and basic rules – player plays against banker and tries to get closer to a sum of 21 than banker but not exceed it. Banker has certain limitations which strategy it has to follow but player has to act before banker.

Blackjack Rules

Blackjack is a card game played with between 1 to 8 standard decks of playing cards. Cards are shuffled and placed to a so called “shoe”, where they are then dealt from for each deal. At online casinos, the shoe is shuffled after each hand at most cases. Cards of rank between 2 to 10 are valued at their face value and all the face cards are valued as 10. An ace is valued 1 or 11. The highest possible hand is an ace and any 10-point card. This is so called “blackjack”. A winning blackjack pays 3:2. The player wins if his hand has more points than the dealer, without going over 21 (busting). If both player and dealer have a blackjack or both have the same point value hand, the hand is a push. Aside from a blackjack, a winning hand pays 1:1. If player busts, dealer wins automatically that hand. If player has an ace in his hand, for example ace+6, he has so called “soft hand” (an ace is either a 1 or 11), meaning that he either has a sum of 7 (soft total) or 17 (hard total). If player draws a card which would make his hard total over 21, then the ace plays as a 1 the rest of the hand.


1) After player has decided and placed a bet, the both player and dealer are dealt two cards. Dealers other card is face down and player´s both cards are dealt face up. If the dealer has an ace or 10-point card showing, he will peek for a possible blackjack (under standard online rules). If the dealer has an ace as a showing upcard, the player has an opportunity to buy “insurance” against the blackjack. If player decides to buy insurance and the dealer’s remaining card is a 10-point card forming a blackjack, then insurance bet pays 2:1. Under standard online rules, taking insurance is not profitable. The only situation when taking insurance is profitable is when:

A) A shoe contains only 1 deck, player plays 3 hands at a time and there are no visible 10-point cards showing.

B) A shoe contains only 1 deck, player plays 5 hands at a time and there are 0 to 2 visible 10-point cards showing at the table.

C) A shoe contains 2 decks, player plays 5 hands at a time and there are 0 visible 10-point cards showing at the table.

Usually online blackjack is played with 4 to 8 decks, so taking insurance is not profitable if player likes to follow optimal strategy.

Some online casino also offer “even money” bet, if player has a dealt blackjack and dealer has an ace showing. This bet also pays 2:1, but is never profitable, if player likes to follow optimal strategy.

2) Now if the dealer does have a blackjack, the hand will end. If the dealer does not have a blackjack, then the player has a few options to choose from what to do with his hand:

Stand: The player can keep his current two cards, not taking more giving turn to the dealer.

Hit: The player can take one or more cards to his hand. The player can continue hitting until reaching 21 or busting.

Double: The player can double his bet and take one another card. The player is not allowed to hit after a double and can only double on a 2-card hand.

Split: If the player has two cards of equal rank, he can split the cards into two separate hands. The bet is also doubled to make one equal bet for each of the two one card hands. After the split, the player is automatically given second card in each hand to form two 2-card hands. If the player splits a pair of aces, only one more card is given to each hand (under standard rules). If the player splits any other pair, he can choose to hit, stand, or double on each of the hands. A second split may be allowed as well if again one or both of the new two card hands compose a pair (depending on the rule variations of each casino and blackjack game).

3) When player has decided actions to each of his hand to the end (finally standing or busting on each hand) the bankers face down card is turned face up and banker draws more cards until having a sum of 17 to 21 (under standard rules) of busting his hand.

Rule Variations

There are many possible rule variations to standard rules:

Number of decks: The number of decks used can vary from 1 to 8 depending on the form of blackjack played.

Hit or stand on soft 17: Usually rules require the dealer to stand on all 17s (hard or soft total). Some rule variations require the dealer to stand on a “hard” 17, but hit a “soft” 17.

Peek for blackjack: Under standard rules, the dealer peeks for blackjack when an ace or 10-point card is showing. Under some rules, dealer does not peek for blackjack.

Doubling: Typical online rules allow players to double on any two cards. Some variations limit doubling on hard sums of 9 to 11, and not on soft sums including an ace. Possibility to double on any two cards favors the player.

Surrendering: Some blackjack forms give player an option to surrender and lose half of the bet at the start of the hand (after 2-card hand is dealt). The surrender option is typically given after the dealer checks for blackjack, which is called a “late surrender.” A few game variations offer an “early surrender” before the dealer checks for blackjack.

Charlie: 7-card Charlie is a hand composed of 7 cards without busting. If this rule is in use, player´s hand is considered as an automatic winner. Other Charlie rules might also be rarely available.

Re-splits: After splitting your cards to form two separate hands, you may draw a matching card again and wish to split again. Some variations allow this, others do not. Some variations allow certain amount of resplits only. Usually re-splitting aces is not allowed, but rarely it is.

Hitting split aces: Under standard rules, player is only allowed to draw a single card to split aces. Some rare variations allow you to draw multiple cards to split aces.

Side bets: Some blackjack games offer an optional side bet, which pays if the player’s hand contains a certain combination of cards. For example, if players hand is 7-7-7. You might want to take a side bet for fun, but when played using optimal strategy, side bet is a –EV choice. Exceptionally high progressive jackpot might make a difference to this rule of thumb.

House Edge and Optimal Strategy

Blackjack usually has a house edge of ~0.5%. Optimal strategy for different online casino softwares and game variations are listed below in the table. House edge assumes using optimal strategy listed in the link for each variation. You can also use blackjack strategy tool yourself to get optimal strategy for different rule variations (rules are always listed somewhere on the casino homepage or software). Following house edges have been calculated using general guidelines available at Wizard of Odds and using Winner Gambling´s team´s unique programmed blackjack simulator, which simulates millions of hands of BJ using different rule variations.

Bet Sizing and Variance

Blackjack has pretty low variance. It has standard deviation of about ~1.15 per unit wagered. There are only a few casino games with this low variance, like roulette (1:1 bets), pai gow and baccarat. Still, with large bet sizes, variance is a huge factor when wagering for example toward bonus requirements. See casino software reviews for more info about the game speed with different softwares.