While slot machines and online slots in virtual casinos are perhaps the most accessible casino game, it’s fair to say that one of the most widely played table games in the world is Blackjack.

There are a number of reasons for this. It’s easy to learn the rules, the fast pace of the game, the low house edge, and the fact that there is an element of skill required to win. This makes it extremely appealing to gamblers of all ages.

In all forms of Blackjack, the end goal is exactly the same. You must try to reach a total of 21 or a higher total than the casino dealer without going bust.

As simple as the game is, there are different types of Blackjack. And those differences can be seen in the rules. Altering certain ones will allow a casino to increase its edge over the player, sometimes quite dramatically.

Understanding Blackjack Rule Variations

If you learn and employ the perfect Blackjack strategy, the house’s advantage over you would be less than 1%. This is a major reason why this game is so popular!

The most common rule variation is the number of decks used once. Having just one deck of cards in play is an extreme rarity. It only gives the house a 0.17% advantage. But adding an extra three decks to this one increases that edge to 0.66%.

After the number of decks used, the most prevalent rule change is the payout when a player hits Blackjack.

The vast majority of live and online Blackjack casinos payout at odds of 3:2 when a player hits a natural Blackjack, but some casinos actually change this payout to 6:5, which does not sound too drastically different, but it adds an extra 1.4% advantage to the house.

If you find a game that only offers 1:1 for hitting Blackjack, walk away because the house now has an extra 2.3% edge over you. Let’s say that the chances are they will more than likely be using other rules to extract more cash from you.

Basically, before you wager any money on a game of Blackjack, you should always ask the dealer to clarify the rules the house is playing to. Most will display the information on the table, but some you will have to ask for.

Specifically, ask if you will only receive one card after splitting aces (if you can receive more than one, you have an extra 0.13% edge) and if you can double-down on a split pair (another 0.12% in your favour if you can).




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Blackjack Rule Variations

Variation Effect
Blackjacks pay 2 to 1 +2.27%
Triple down on any two cards +1.64%
Five card Charlie1 +1.46%
Optional half win for 5-card Charlie9 +0.77%
Suited blackjacks pay 2 to 1 +0.57%
Player 21-points is automatic winner +0.54%
Single deck +0.48%
Early surrender against ace +0.39%
Player 21 vs. dealer blackjack is a push +0.35%
5-card win pays 3-2 +0.33%
Blackjack tie pays 3 to 2 +0.32%
Six-card Charlie pays 3 to 2 +0.31%
Early surrender against ten +0.24%
5-card (or more) 21 automatically pays 2 to 1 +0.24%
Player may double on any number of cards +0.23%
Ace and 10 after splitting aces is a blackjack +0.19%
Player may draw to split aces +0.19%
Double deck +0.19%
Six card Charlie1 +0.16%
Player may double, double for less, or stand after splitting aces +0.15%
Tied blackjack pays 1-2 +0.11%
Double Down Rescue +0.10%
6-card win pays 2-1 +0.09%
Player may resplit aces +0.08%
Player may double or stand after splitting aces +0.08%
Late surrender against ten +0.07%
Four decks +0.06%
7-card win pays 5-1 +0.05%
777 pays 3 to 1 automatically +0.05%
Five decks +0.03%
777 pays 2 to 1 automatically +0.03%
Six decks +0.02%
Seven card Charlie1 +0.01%
Late surrender against ace +0.00%
Dealer must stop with six cards +0.00%
Late surrender after splitting +0.00%
Split to only 3 hands -0.01%
No-peek: ace showing2 -0.01%
BB+13 -0.01%
Dealer secretly goes first5 -0.02%
OBBO4 -0.03%
European no hole card (splitting)7 -0.03%
European no hole card (doubling)7 -0.08%
Player may double on 9-11 only -0.09%
No-peek: ten showing6 -0.10%
Player may not resplit -0.10%
European no hole card7 -0.11%
Player may not double after splitting -0.14%
Player may double on 10,11 only -0.18%
Player may not split aces -0.18%
Dealer hits on soft 17 -0.22%
Blackkjack pays 7-5 -0.45%
Player may not split -0.57%
Red blackjack pays 2-1, Black blackjack pays 3-2, Mixed blackjack pays 1-1 -0.57%
Blackjack pays 6-5 -1.39%
Player may not double -1.48%
Player loses 17 ties -1.87%
Player may not double nor split -1.91%
Blackjacks pay 1 to 1 -2.27%
Player loses 17,18 ties -3.58%
Player loses 17-19 ties -5.30%
Dealer bust on 22 is a push8 -6.91%
Player loses 17-20 ties -8.38%
Player loses 17-21 ties -8.86%

Key Point Notes

1. Five Card Charlie: A “Charlie” is an automatic winner. For example, the five-card Charlie rule means the player automatically wins with 5 cards, as long as he didn’t bust.

2. No-peek: ace showing: The dealer does not peek for blackjack with an ace up. If the dealer has an ace-up blackjack, the player loses all bets made, including from doubling and splitting. A 10-up blackjack will be revealed immediately after peeking, and the player will lose only his original wager, except a blackjack tie will push.

3. BB+1: BB+1 refers to an Australian rule, in which the player will lose all busted bets, plus one unit if the dealer gets a blackjack.

For example, if the player splits 8’s to three hands of a 20, (doubled) 19, and a busted hand, and the dealer gets a blackjack, then the player will lose 2 units, one for the busted hand and one from the remaining 3 units on the table. There is a great deal of confusion about the term for his rule, some sources calling it “OBBO,” for Original and Busted Bets Only.

4. OBBO: OBBO stands for Original Bets and Busted Only. “Original Bets” means each original bet per hand. So, if the player bets £5 and splits into three hands, he would have three original bets of £5 each. As far as I know, the OBBO rule is confined to some parts of Australia and Malaysia.

In the example above, the player would lose 3 units under this rule, one for the busted hand and two for the number of unbusted hands. The term is discussed in depth in the book The Pro’s Guide to Spanish 21 and Australian Pontoon by Katarina Walker.

5. Dealer secretly goes first: This strange rule is actually followed in Pennsylvania on Shufflemaster TMS-300 video multi-player blackjack games. State law prohibits one player from taking the cards of another player. The way they implement this rule is to give every player, and the dealer, a separate shoe.

The dealer plays out his hand first, secretly, and the results are stored in memory. Then the cards used by the dealer are removed for each player shoe. When all players have finished acting, the game shows what cards the dealer drew already. According to Shufflemaster, the effect of this rule is 0.02% in favour of the dealer. Shufflemaster wishes to add this rule is part of patent-pending technology.

6. No-peek ten showing: The dealer does not peek for blackjack with a 10 up. If the dealer has a 10-up blackjack, the player loses all bets made, including from doubling and splitting. An ace-up blackjack will be revealed immediately after peeking, and the player will lose only his original wager, except a blackjack tie will push.

7. European no hole card: Dealer does not take a hole card or never peeks at it if he does. If the dealer has a blackjack, then the player loses all bets made, including from doubling and splitting, except a blackjack tie will push.

The cost of this rule to the player is 0.08% when doubling, and 0.03% when splitting. This breakdown is important in the case of Galaxy casinos in Macau, where the player only loses the original bet when doubling, but everything when splitting, if the dealer gets a blackjack.

8. Dealer bust on 22 is a push: The push on a dealer 22 rule is a legally protected rule. The rights belong to the owner of Blackjack Switch.

9. Optional half-win for 5-card Charlie: This rule can be found at the Pharaoh’s Palace in Macau. The player may invoke the rule before the dealer checks for blackjack. The effect shown is based on the dealer not taking a hole card.