The house edge in blackjack is typically around 0.5%, assuming you use basic strategy, which is the optimal way to play each hand. This edge can vary depending on factors like the number of decks used, table rules, and whether advanced techniques like card counting are employed. To lower the house edge, it's important to follow basic strategy, avoid insurance bets and side bets, and choose games with favorable rules such as 3:2 payouts for blackjacks and fewer decks. For more experienced players, card counting can further reduce the house edge, although it's difficult to master and may lead to being banned from casinos.