There's no denying Blackjack's popularity and it's always been a casino favourite amongst players who are looking to get one over the dealer. While the rules have stayed much the same since its inception, Blackjack has evolved through the use of multi-decks and side bets. If you're playing Blackjack online, you'll find lots of innovative twists on the classic game - in order to make it remain popular and appeal to the 21st century gamer. If you're playing a new variant, you'll notice the number of decks varies from one game to the next. So, let's take a look at why, when it comes to Blackjack, size really matters.

Fewer decks = more chance of Blackjack

You are more likely to land a natural Blackjack when fewer decks are in play. In a single deck, there are four aces and 16 cards with a value of 10 (the 10s of each suit, as well as Jacks, Queens and Kings) - so 20/52 cards can create a natural. With two decks, it's 40/104 and so on, with the probability decreasing with every additional deck.

If we look at it by the law of percentages, the probability of landing a natural Blackjack with a single deck of cards is 4.83%. This decreases to 4.78% with two decks, and could drop as little as 4.75% with six decks. If you're looking to land that 3:2 pay-out, the single-deck Blackjack is the one to play.

But don't play single-deck games if the pay-out for a natural is 6:5 - if that's the case, you'd be better off sticking to multi-deck games!

Fewer decks = more chance when you double down

By a similar reasoning to above, if you're dealt a 5, 6 and choose to double down, you're more likely to land that 10-value card if you're playing single-deck Blackjack, in comparison to multi-deck games. Dealers don't have the option of doubling down either, so the odds are very much in your favour.

Fewer decks = lower house edge*

There was a time that single-deck Blackjack was the holy grail of all casino games, but multi-deck games were introduced to make it harder for players to count cards, or use strategy, and also increase the house edge.

Single-deck Blackjack games can have a house edge as low as 0.15%, but as soon as additional cards are thrown into the mix, this can increase. Games that utilise up to six or eight decks can have an increased house edge of 0.50% - over three times that of a single-deck game.

Although, interestingly, we mentioned the different pay-outs for a natural earlier and if you're playing a single-deck game which offers a pay-out of 6:5, as opposed to the usual 3:2, the house edge jumps from 0.15% to 1.45% - crazy, huh.


Fewer decks mean a greater chance of being dealt a natural, but adding decks can affect your odds. Unfortunately, the 6:5 pay-out is more common in single-deck games so if you're wanting better money, multi-deck Blackjack is more favourable. If you can find a single-deck game offering a pay-out of 3:2, or you're a basic strategy player, you should plump for single-deck games. At the end of the day, it's all about preference and whatever game you choose to play, you'll always have the same aim - to beat the dealer!