Blackjack online

Blackjack belongs to the small group of casino games, video poker among them, in which the house edge is not a property of the table alone but the result of two things, the rules printed on the felt (or in the help screen of an online game) and the decisions of the player. The same game can leave the casino half a per cent of every stake or more than five, depending on a few lines of rules and on the player.

Throughout this page we follow a hypothetical player who bets $25 a hand for sixty hands an hour, which puts $1,500 in play and turns every percentage into dollars. The figures are our own calculation for an infinite deck, set beside the eight-deck figures that the Wizard of Odds publishes, so that each rule can be checked twice.

The lines of the rules that move the edge

The costliest line is the payout on a "blackjack" (an ace with a ten, jack, queen or king as the first two), which arrives about once every 21 hands. At 3:2 our player's $25 wins $37.50; at 6:5 it wins $30, and the $7.50 missing once every 21 hands adds about 1.4 points to the edge. That is nearly three times the edge of a game played well.

The second line is the dealer's "soft 17" (a seventeen in which an ace counts as eleven, such as ace and six), because a dealer who must hit it rather than stand adds about 0.22 points. The third is "doubling after a split" (the right to double a hand created by splitting a pair), whose absence adds 0.14 points.

The fourth, "surrender" (giving up half the bet once the dealer has checked for blackjack), gives back about 0.08 points where it is offered. The number of decks matters, though less than its reputation suggests: a single deck is 0.48 points cheaper than eight, and six decks only 0.02.

The European rule of "no hole card" (the dealer draws a second card only after the players have acted, so that a dealer blackjack also takes the money added by doubles and splits) costs about 0.11 points, and the table below gathers these lines with the published figure and ours side by side.

How single rules move the house edge, in percentage points (a plus sign is a cost to the player)

Rule on the table	Eight decks, published table	Our calculation, infinite deck
Blackjack pays 6:5 instead of 3:2	+1.39	+1.35
Dealer hits soft 17	+0.22	+0.22
No doubling after a split	+0.14	+0.14
No hole card, doubles and splits lost to a dealer blackjack	+0.11	+0.11
Late surrender offered	-0.08	-0.09
Aces may be split again	-0.08	-0.08
Single deck instead of eight	-0.48	not applicable
Six decks instead of eight	-0.02	not applicable

The figures add up closely enough to be used together, so that a table paying 6:5 with a dealer who hits soft 17 costs a player who makes every decision correctly about 2.1 per cent (2.08 in our calculation). In our view the payout on a blackjack is the first line to read, and the only one that justifies leaving a table at once.

Basic strategy and the half per cent

"Basic strategy" is the table of decisions ("hit", "stand", "double", "split" or "surrender") that gives the best expected result for every player total against every dealer card. It is not an opinion but a calculation. With the dealer standing on soft 17, doubling allowed after a split and splits up to four hands, our calculation for an infinite deck gives 0.51 per cent, and a shoe of six or eight decks is slightly cheaper.

For our hypothetical player, half a per cent of $1,500 is about $7.50 an hour, the price of the game when every decision follows the table. A player who copies the dealer instead, hitting every hand below seventeen and never doubling or splitting, faces 5.67 per cent in our calculation, which is $85 an hour for the same sixty hands, eleven times as much!

The strategy card itself is short, because most of its cells repeat a few rules (stand on a hard 17 or more, double an 11 against anything but an ace, always split aces and eights). If you play from the card, the edge is the half per cent above; if you play from memory, it is worth checking the card again after a few sessions.

Insurance, the bet that looks like protection

When the dealer shows an ace, the table offers "insurance", a side bet of half the stake that pays 2 to 1 if the hidden card is worth ten. The bet breaks even at one ten in three. In a six-deck shoe, with only the dealer's ace known, 96 of the 311 unseen cards are tens (30.9 per cent), so insurance loses 7.4 per cent of what is staked on it.

"Even money", offered to a player who holds a blackjack against an ace, is the same bet under another name, and slightly worse, since the player's own ten is missing from the shoe (7.8 per cent in six decks). A player who insures every time pays about 0.28 points more on the whole game; we would advise declining it, whatever the cards in your hand.

Card counting against software

"Card counting" works only because the cards already dealt are missing from those still to come, so that a shoe rich in tens and aces, late in the deal, favours the player for a few hands. An "RNG" game (the random number generator dealing the cards) that shuffles before every hand, and a live table with a "continuous shuffling machine" (which returns the cards after each round), leave the counter nothing to count.

A live shoe dealt down to a cut card is where counting could apply, and even there it needs a great many hands, a wide spread of bets and a casino content to watch. We do not consider it a plan for an online player. The same holds for the betting systems that change the size of the bet after a win or a loss, which move money around without moving the edge.

Side bets: Perfect Pairs and 21+3

The "side bets" sit beside the main box and are settled on the first cards alone, and "Perfect Pairs" pays when the opening two cards form a pair, at 25 to 1 for the same suit, 12 to 1 for the same colour and 6 to 1 for mixed colours. With that pay table it keeps 4.10 per cent in an eight-deck shoe and 6.11 per cent in a six-deck one, because fewer decks make pairs rarer.

"21+3" pays when the player's two cards and the dealer's "up card" (the one dealt face up) form a poker hand of three cards; at 100, 40, 30, 10 and 5 to 1, from suited three of a kind down to a flush, it keeps 3.70 per cent with eight decks and 4.62 with six. Our hypothetical player who adds $5 to Perfect Pairs on each hand stakes $300 an hour on the side and pays about $12.30 for it in an eight-deck shoe (about $18.33 in a six-deck one), more than the main game costs with basic strategy.

Blackjack and bonus wagering

A bonus comes with a "wagering requirement" (the amount that must be bet before the bonus can be withdrawn), and the terms say how much of each bet counts towards it, game by game. A player with a bonus of $100 and a requirement of 30 times the bonus must bet $3,000, which at half a per cent costs $15 in expectation and leaves the player $85 ahead on average.

The arithmetic explains why the terms can weight blackjack low or leave it out: if they count it at 10 per cent, the same requirement becomes $30,000 of bets at the table, and the expected loss of $150 is larger than the bonus itself! We would read the contribution table before taking a bonus for blackjack, and our page on wagering requirements works the same calculation for other games.

Live tables and RNG tables

The rules can differ between the RNG tables and the live ones of the same casino, so it is worth reading the help screen of each game for the blackjack payout, the soft 17 rule, the number of decks and the dealer's "peek" (the check for blackjack before the players act). Evolution describes most of its live blackjack tables as seven-seat games with a "Bet Behind" option, which lets a player back another player's hand (and inherit that player's decisions).

A live table deals at the pace of a dealer and a computer table at the pace of your clicks, which changes the cost per hour but not the edge per hand (the live casino page describes how a studio deals and streams). In blackjack the player chooses that edge twice, once with the table and once with each decision, and the house edge page ranks it among the other games.

Questions

By the Rand Casinos editorial team · Last updated October 2026 · Online since 2007