Blackjack house edge: the table rules that change the odds

Where the 0.5% figure comes from

Blackjack is one of the few casino games where decisions change the return. The published edge assumes basic strategy: the mathematically best action for every combination of player hand and dealer upcard. Under common rules — six decks, dealer stands on soft 17, double after split allowed, blackjack pays 3:2 — that edge is about 0.4% to 0.5%.

The edge exists because the player acts first. If both player and dealer bust, the player has already lost.

How each rule moves the edge

Figures are approximate and interact slightly with each other. They are drawn from published rule-variation tables; an exact number needs the full rule set.

Single-deck blackjack: read the payout first

One deck is the best count for the player on paper, which is why single-deck tables are advertised. Many of them pay 6:5 on a natural. Taking 0.46 points off the edge and adding 1.39 leaves the game about 0.9 points worse than an ordinary six-deck 3:2 table.

On a 6:5 table a $10 blackjack pays $12 instead of $15. Naturals arrive about once every 21 hands, so the shortfall adds up quickly.

Multi-hand blackjack

Online multi-hand games let you play several hands against one dealer hand. The house edge per hand is the same as the single-hand version with the same rules. What changes is exposure: three hands at $10 puts $30 in play per round, so the expected loss per round triples.

Because all hands face the same dealer cards, results are correlated. A dealer bust pays every standing hand; a dealer 21 beats them together.

Side bets and insurance

Insurance pays 2 to 1 if the dealer has a ten in the hole. In a six-deck game it carries an edge of roughly 7%, so basic strategy never takes it. Side bets such as Perfect Pairs or 21+3 are separate wagers with their own pay tables and edges that are typically several times higher than the main game.

A short checklist before you sit down

1. Confirm blackjack pays 3:2. Walk past 6:5 and even-money tables.
2. Prefer “dealer stands on all 17s”.
3. Check you can double on any two cards and after splitting.
4. Use a basic strategy chart for the exact rules. Online, the game’s help page lists them and states the theoretical return.

When surrender is offered, knowing when to use it is worth a little more.