The house edge in blackjack variations varies significantly based on specific rules and gameplay mechanics. In traditional blackjack, it typically ranges from 0.5% to 1% with effective use of basic strategy. However, variations like Blackjack Switch and Spanish 21 often have higher house edges due to unique rules, such as lower payouts for natural blackjacks or different payout structures. Players need to understand these variations to optimize their strategies and make informed decisions about their gameplay.