Blackjack is the one casino game where the rules vary from casino to casino. Although gameplay remains the same, differences in rules affect playing strategy and house advantage. Listed below are the rule variations and their effect on house advantage.

A. NUMBER OF DECKS USED
Variables — 1, 2, 4, 5, 6, or 8 decks
Blackjack games can be found using anywhere from 1 to 8 decks. The more decks that are used, the greater the house advantage. Before “Beat the Dealer” was published, the standard Las Vegas Strip Blackjack game was played with one deck. Although single deck games can still be found, other rule changes are usually instituted to ensure a higher house advantage.

B. WHAT THE DEALER DOES WITH A SOFT 17
Variables — Stand or Hit
It is advantageous to a player when the dealer Stands with a Soft 17 [see above right]. This rule is common in Atlantic City and Las Vegas Strip casinos. It is advantageous to the House if the dealer Hits with a Soft 17. This rule is common with 1 or 2 deck games.

C. DOUBLE-DOWN VARIATIONS
Variables — restrictions: 9–11, 10/11, or None; Doubling after a Split: Yes or No
Limitations on what combinations a player can Double-Down on increase the house advantage. In some games players are only allowed to Double-Down on a 10 or 11, or they are not allowed to Double after Splitting.

D. SPLITTING VARIATIONS
Variables — 1, 2, or 3 Splits allowed
In some games players are not allowed to resplit cards (Splitting after a Split) — this is advantageous to the house. In some games resplitting Aces is not allowed which is also advantageous to the house.

E. LATE SURRENDER
Variables — Late Surrender allowed: Yes or No
Late Surrender is only available on an intial 2 card hand. When a player chooses to Surrender, they forfeit half of their bet without playing out the hand. With Late Surrender, a player can only Surrender after the dealer checks for blackjack.

F. DEALER PEEK VS. DEALER NO PEEK RULE
Variables — Peek, No Peek, Full No Peek
In most games the Dealer will check for Blackjack when her upcard is an Ace or a Ten. This is advantageous to the player. In some games the Dealer will not check for a Blackjack when her upcard is a Ten or not even check when it is an Ace (Full No Peek). This is advantageous to the house. “No Peek” rules are advantageous to the House because a player may lose more than his original bet (through Splitting or Doubling Down) against a Dealer’s Blackjack.