Blackjack — Rules, Strategy & the Edge

Blackjack is the rare casino game where skill matters. With basic strategy on good rules the house edge is around 0.5% — the best on the floor. But that edge is exquisitely sensitive to the rules: the blackjack payout (3:2 vs 6:5), whether the dealer hits soft 17, the number of decks, and the doubling/splitting rules each move it. Read the felt, not the game name.

Because you choose how to play each hand — hit, stand, double, split — the outcome is not fixed at the deal. 'Basic strategy' is the mathematically optimal decision for every player hand against every dealer upcard; playing it perfectly pulls the edge down to roughly 0.5% (lower on liberal rules). Every deviation hands the house more.

3:2 blackjack pays 1.5× on a natural; 6:5 pays only 1.2×, adding about 1.39% to the house edge — turning a 0.5% game into roughly 1.9%. Dealer hitting soft 17 (H17) adds about 0.2%; going from one deck to eight adds up to about 0.5%; restricted doubling and splitting, and no surrender, all cost the player.

Stand more against the dealer's weak cards (2–6), hit more against strong cards (7–A); double strong two-card totals when the dealer is weak; always split aces and eights. A basic-strategy card is legal and encouraged, and using it is the single biggest thing a player can do to shrink the edge.

Counting tracks the ratio of high to low cards remaining, so a player can bet more when the deck favours them; done well it can flip the edge slightly positive. It is not illegal, but casinos treat it as advantage play and will restrict or bar suspected counters — which is exactly why any edge, once found, gets closed.