Blackjack rules

Blackjack is played with six packs of 52 cards without the jokers. The Jack the Queen and the King is worth 10 and the Ace is worth 11 or 1, while the rest of the cards are worth as much as the cards indicate (the player may determine the value of the ace they have in their possession).

blackjack card values

During blackjack, a player plays against the bank (in casinos you can choose whether you want to play alone or with others) and is not in contact with other players. The goal is to get the value of the player’s cards closer to 21 than the bank’s cards. The six packs of shuffled cards are placed in a bag and the dealer pulls cards from this until two thirds of the cards from the bag are gone. The six pack of cards are then shuffled again. The game is played for the bet determined for the deal before the deal is made. If the player loses then they lose their bet, but if they win, they will get back double of their bet. At the beginning of the game the player will receive a card face up, the bank a card face down meaning that the player cannot see the bank’s first card. Next, the player may request a card or stop. The bank will not receive a new card until the player has not stopped, that is they have not stopped their game in the current round. The player can stop at any time and not request more cards and their total value will be the sum of their current cards. If however, the player asks for another card and the total value of their cards exceeds 21, then the player loses regardless of the later results of the bank (the bank then immediately receives the bet of the player). After the player has stopped the bank will reveal the faced down card, then they must play according to set rules. If the total value of their cards is less than 17 then they must draw a new card until the total value is at a minimum of 17. If they have at least 17 in total value and between 17-21 the bank must stop regardless of whether the player is closer to 21 or not. For example, if the player has 18 and after drawing two 5’s the bank draws a 7 then the bank must stop, and the player has won. If by playing these rules the bank exceeds 21 and the player is still in the game, then the player has won again. Blackjack is also played by other rules, but these are the official rules.


Every player makes a bet and then each player is dealt 2-2 cards and the dealer 1 all face up. The players each decide on the next steps:

Draw another card

  • Raise the bet (double down max) and receive another card
  • In case of a pair they split the cards and make a second dealing with the same bet (4-8 splits maximum, in the case of Aces only 1-1 card can be drawn).
  • If the first card of the dealer is an Ace then they can ask for insurance which can be half of the bet limit, if the dealer has blackjack then they win double the amount of the insurance bet (they of course lose the original bet)
  • Even money: If a blackjack was dealt and the dealer has an ace, because of the insurance bet we will be guaranteed to win the original bet.
  • The player does not request more cards and stops
  • The dealer asks for cards until they reach at least 17

Winning inequalities

  • If both the dealer and the player exceed 21 then the player always loses. There is a 28% chance of busting meaning this scenario has 0.28*0.28 which is around 8% chance of occurring. With an appropriate strategy this can be reduced to 0.5%. By counting cards, we can also gain an advantage.
  • A modifying factor is the 1.5x pay-out of the bank. In this case the winning is asymmetric as the bank does not win 1.5x of the bet but only 1x.
  • Furthermore, doubling the bet at the right time can be advantageous for us. The bank cannot double our losses (thankfully).
  • It is possible to split, which similarly to doubling can tip winning in our favour.
  • We can stop at 16 and the bank must always draw.

The advantage of the bank

  • If the bank stops as “Soft 17” that means a 0.2% advantage for players.
  • Soft 17: if the bank reaches 17 by valuing an Ace at 1.
  • The less packs of cards are being used the smaller the advantage of the bank
  • They compensate for this with stricter rules and smaller winnings.