Games
Blackjack House Edge and Basic Strategy
Blackjack carries the lowest house edge on the casino floor: about half a percent against a player using basic strategy at a table with standard rules. That figure is not an estimate. The optimal play for every possible hand was computed in the 1950s and has not changed since — blackjack is a solved game, and the solution fits on one card.
Written by the Moes Almanac editorial team
0.5%
A player guessing instead of following basic strategy faces roughly five times that. Almost all of the difference is decision-making, not luck.
Every other game asks what you bet. Blackjack asks what you know.
The rules, in one pass
You and the dealer each receive two cards, with one of the dealer's cards face up. Cards two through ten count their face value, picture cards count ten, and an ace counts one or eleven — whichever helps your hand. You win by finishing closer to 21 than the dealer without going over.
The dealer makes no decisions. They follow a fixed instruction printed on the felt: draw until reaching 17, then stop. This is the most important structural fact about blackjack. You are playing against a procedure with no discretion, and that is precisely what makes the game solvable.
- A blackjack — an ace with any ten-value card in the first two cards — pays 3:2 at a fair table.
- Going over 21 loses immediately, before the dealer plays their hand. This is the entire source of the house edge.
- You may split pairs, double your stake on a promising hand, and at some tables surrender half of it.
Where the edge actually comes from
The house does not win because the dealer draws better cards. It wins because you act first: when you bust, your stake is gone even if the dealer busts moments later. Everything else in the rule book adjusts that basic asymmetry up or down.
Rule variations matter far more than most players assume. The table below shows what each one does to the house edge, measured in percentage points. A single rule can cost you more than years of improving your play.
| Rule | Effect |
|---|---|
| Blackjack pays 6:5 instead of 3:2 The most expensive rule on any table | +1.39% |
| Six decks instead of one | +0.55% |
| Dealer hits soft 17 | +0.22% |
| Doubling after a split not allowed | +0.14% |
| Late surrender allowed | −0.08% |
| Re-splitting aces allowed | −0.08% |
Basic strategy is a lookup table, not a feeling
Basic strategy gives the mathematically best action for every combination of your hand and the dealer's up card. It is not a winning system — nothing beats a negative expectation over time — it is the set of plays that loses the least. Learning it is the whole difference between the two house edge figures above.
A handful of rules cover most hands you will actually be dealt:
- Always split aces and eights. Never split fives or tens.
- Stand on hard 17 or higher, without exception.
- Hit hard 12 through 16 when the dealer shows 7 or higher; stand when they show 6 or lower.
- Double on 11 unless the dealer shows an ace.
These are anchors, not the whole chart. The complete table runs to roughly 250 cells, and every cell you guess at costs you money.
Insurance is not insurance
When the dealer shows an ace you will be offered "insurance" at 2:1. It is a separate side bet on whether the dealer's hole card is a ten, and it has no connection to protecting your original stake. In a six-deck game it carries a house edge many times that of the hand you are already playing. Decline it every time.
Frequently asked questions
- What is the house edge in blackjack?
- About 0.5% at a table with standard rules, against a player using basic strategy. Without basic strategy, the same table takes roughly 2.5%. The exact figure depends on the rule set, and above all on whether a blackjack pays 3:2 or 6:5.
- Why does a 6:5 blackjack payout matter so much?
- Paying 6:5 instead of 3:2 on a blackjack adds about 1.39 percentage points to the house edge, which roughly triples the cost of playing an otherwise standard table. A natural blackjack lands on nearly one hand in twenty, so the reduced payout is felt constantly even though it touches only one outcome.
- Is card counting illegal?
- No. Counting cards is mental arithmetic and is not a crime anywhere. Casinos are private businesses and may refuse service to players they suspect of counting, and online tables shuffle after every round, which removes the opportunity entirely.
- Should I ever take insurance?
- No, unless you are counting cards and know the remaining shoe is unusually rich in ten-value cards. Taken on its own, insurance carries a house edge of about 7.4% in a six-deck game, against roughly 0.5% for the hand it is offered alongside.