Unlike most table games, the playing rules in blackjack are not always the same from one casino to the next. In fact you'll usually find different rules within the same casino. Some rules in fact will be more favorable for the player while others favor the casino. It's these mix of rules that ultimately determines the casino's edge in the game so it's important that you know which rules favor the player and which the casino.
Player favorable rules.
Doubling on any first two cards.
Doubling down after pair splitting
Double on 3 or more cards
Blackjack pays 2 to 1
Casino favorable rules.
Increasing the number of decks of cards
Dealer hits soft 17
Double only on 10 and 11
No resplitting of pairs
Dealer wins ties
European no-hole card rule
The more decks being used the less favorable the game is for players. A single deck Las Vegas Strip game has these rules: dealer stands on soft 17, doubling allowed on any 2 cards, you can not double down after pair splitting, pairs can be resplit, split aces receive only one card, no surrender, player blackjack is paid at 3 to 2 and insurance is paid at 2 to 1. With these rules, a basic strategy player has a slight 0.02% edge over the casino. As the casino increases the number of decks of cards, the edge swings toward the house.
# Decks Effect in Percent
Notice the dramatic increase in the casino's edge when you go from 1 to a 2 deck game. The difference decreases as you increase from 2 to 3 decks and then 3 to 4 and so on. The casino's edge basically levels off at about 8-decks which is one-reason casinos do not use more than 8-decks of cards.
The following table can be used as a guide to determine the approximate effects different rules have on the basic strategy player (note: The effect varies slightly depending upon the number of decks of card. The information in the table is an average).
Dealer hits soft 17 -0.20%
European no-hole card -0.11%
Late surrender +0.06%
Early surrender +0.62%
Resplit aces +0.05%
Double down after pair splitting +0.14%
Double 3 or more cards +0.24%
Blackjacks pay 2 to 1 +2.30%
Blackjack pays even money -2.30%
No resplits -0.03%
Double only on 10 and 11 -0.21%
You can use can use the information in the table to estimate the casino's advantage. For example assume you are playing in an 8-deck game where double down after pair splitting and late surrender is allowed. The approximate casino's edge is:
8-deck game -0.57%
Double after pair splitting +0.14%
Late surrender +0.06%
Casino advantage -0.37%
Suppose instead the game was dealt with 2-decks with double after pair splitting and resplit of aces. Using the information in the tables you'd arrive at a casino's edge of 0.12%.
As you can see rule variations can have a significant effect on the casino's edge and on your expectations of winning. Therefore always play the best game available.