Blackjack odds
Blackjack is the rare casino game where the numbers are public, stable and worth knowing. None of what follows is a system for winning — the edge belongs to the house in every version of the game — but it does explain where that edge comes from, and why two tables advertising the same game can differ by a factor of four in what they cost you.
What the house actually keeps
House edge is the share of your original bet the casino expects to keep over a long run. It says nothing about tonight. On the rules this table deals, a player following basic strategy exactly faces about a third of a percent — which is to say a hundred hands at ten chips a hand costs roughly three chips on average.
Perfect basic strategy
0.3%
Six decks, dealer stands on soft 17, 3:2, DAS, late surrender.
Typical casual player
2%
The same rules, played by feel rather than by the chart.
The 6:5 trap
1.7%
Identical rules, except blackjack pays 6:5. Avoid these tables.
What each rule is worth
Rule changes move the edge by known amounts. Negative numbers are good for the player. This is how you read a table before sitting down: find the payout first, then the soft 17 rule, then everything else.
| Rule | Effect on house edge | In force here |
|---|---|---|
| Dealer stands on soft 17 | −0.22% | Yes |
| Blackjack pays 3:2 rather than 6:5 | −1.39% | Yes |
| Double allowed after a split | −0.14% | Yes |
| Late surrender available | −0.08% | Yes |
| Double on any two cards, not just 9-11 | −0.09% | Yes |
| One deck instead of six | −0.48% | No |
| Split aces may be resplit | −0.08% | No |
| Dealer does not peek for blackjack | +0.11% | No |
Figures are the standard published values in percentage points, assuming basic strategy throughout. They add up roughly, not exactly, because rules interact.
The dealer's bust chance
The dealer has no choices to make: draw to 16, stand on 17. That makes the upcard the single most informative thing on the table, and it is why basic strategy is organised around it. Five and six are the cards you want to see.
| Upcard | Dealer busts |
|---|---|
| 2 | 35.4% |
| 3 | 37.5% |
| 4 | 39.4% |
| 5 | 41.6% |
| 6 | 42.3% |
| 7 | 26.2% |
| 8 | 23.9% |
| 9 | 23.3% |
| 10 | 21.4% |
| A | 11.5% |
Your bust chance on a hit
Taking one more card on a hard total carries a known risk. This is only half the decision — standing on 16 is also usually a loss — but it explains why 12 through 16 are called the stiff hands and why they feel so unpleasant.
| Hard total | Bust if you hit |
|---|---|
| 11- | 0% |
| 12 | 31% |
| 13 | 39% |
| 14 | 56% |
| 15 | 58% |
| 16 | 62% |
| 17 | 69% |
| 18 | 77% |
| 19 | 85% |
| 20 | 92% |
Why insurance is a bad bet
Insurance pays 2:1 and wins when the dealer's hole card is worth ten. In a six-deck shoe that happens a little under 31% of the time, so a bet that needs 33.3% to break even loses about 7% of every chip you put on it. It is a side bet on a different game, and the answer is no. The exception belongs to card counters tracking a shoe rich in tens, which is not a situation you will meet here.
A third of a percent still swings
A 0.3% edge does not mean losing a third of a chip every hand. Individual hands pay −1, −0.5, 0, +1 or +1.5, and the standard deviation over a hundred hands is far larger than the expected loss. Winning sessions are ordinary and prove nothing; losing sessions are equally ordinary. That gap between the average and the noise is the whole business model of a casino.
Blackjack basic strategy
Basic strategy is the mathematically best play for every combination of your hand and the dealer's upcard. It cannot make blackjack a winning game, but it cuts the house edge to roughly a third of a percent — far better than playing on instinct.
Strategy →Strategy trainer
Basic strategy is a lookup table, and a lookup table is only useful once you no longer need to look it up. The trainer deals an opening hand against a dealer upcard and asks for the play. Answer, see whether you were right, move on. Nothing is at stake and no round is played out — this is purely the decision.
Trainer →More games in the network
The same calm design, a different table each time.
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