Numerous variations on blackjack have sprung up in recent years, such as Spanish 21, Super Fun 21, Blackjack Switch, Double Exposure and others. Most of these games, while novel, have a higher house advantage and require a different strategy than regular blackjack. Spanish 21 can offer a comparable or lower house advantage than regular blackjack when played with the optimal strategy, but all other blackjack variants should be avoided by serious players.

A popular rule variant that is proliferating in today's casinos is 6:5 single-deck blackjack. Instead of a 3:2 payout on a blackjack, the lower 6:5 payout actually increases the house advantage by a substantial margin, making the game unprofitable for serious players. Despite this, the popularity of 6:5 blackjack grows, based on novice players' assumptions that a single-deck game has better odds. Avoid 6:5 single-deck blackjack games, and stick with 3:2 blackjack games with fair rules.