The house edge in a game of blackjack is calculated using the formula: (probability of dealer winning - probability of player winning) * average bet size. For example, let's say that the player is playing a 6-deck game of blackjack with the following rules: dealer hits on soft 17, double after split allowed, no re-splitting aces, no surrender. The house edge for this game is around 0.5%. So the formula would be: (0.49 - 0.46) * $100 = $0.03.