Blackjack is the one mainstream casino game where what you do changes the odds. Play each hand correctly at a table with decent rules and the house keeps around half a percent of what you stake over time. Play on hunches at a table with stingy rules and it can keep several times that. The casino wins in the long run either way. Your decisions only set how much the entertainment costs.
How a hand works
You and the dealer each get two cards. Number cards count at face value, pictures count ten, and an ace counts one or eleven, whichever helps. You are trying to finish closer to 21 than the dealer without going over. An ace with a ten-value card on the first two cards is a blackjack, which beats any other 21 and normally pays 3 to 2.
One dealer card is face up. On your turn you can:
- Hit to take another card, or stand to stop.
- Double down: double your bet and take exactly one more card.
- Split a pair into two hands, each with its own bet.
- Surrender, where offered: give up half your bet and fold the hand.
Then the dealer plays to fixed rules, drawing until reaching 17 or more. The dealer has no choices to make. The house edge comes from one fact: you act first, so if you bust, you lose even when the dealer goes on to bust as well.
The parts of basic strategy that do the heavy lifting
Basic strategy is the mathematically best play for every combination of your hand and the dealer's up card. It was worked out by computer simulation decades ago and is not a matter of opinion. Full charts are easy to find and most online tables will not mind you keeping one open, but a handful of rules deliver most of the benefit.
Hard hands. Stand on 17 or more. With 12 to 16, stand if the dealer shows 2 to 6 and hit if the dealer shows 7 or higher. The usual exception is 12 against a 2 or 3, where you hit. The dealer's small cards are bust cards, so you let the dealer take the risk.
Doubling. Double 11 against almost anything. Double 10 unless the dealer shows a ten or an ace. Double 9 against 3 to 6.
Pairs. Always split aces and eights. Never split tens or fives. A pair of tens is 20 and should be left alone. A pair of fives is 10 and should be doubled, not split.
Soft hands. With an ace counted as eleven you cannot bust on the next card, so be more aggressive. Soft 17 or below is always a hit or a double, never a stand. Soft 18 is a stand against 2, 7 and 8, a hit against 9, 10 or ace, and often a double against 3 to 6.
Insurance. Decline it, including "even money" on your blackjack. It is a side bet at poor odds.
None of this is a way to win. It is how you avoid paying more than the game requires.
Rule variations and what each one costs
Not all blackjack tables are the same game. The rules are listed in the help screen, and they move the house edge by amounts worth knowing. The figures below are approximate and assume basic strategy.
| Rule | Effect on the house edge |
|---|---|
| Blackjack pays 6 to 5 instead of 3 to 2 | Adds roughly 1.4 percentage points. The worst common rule by a distance |
| Dealer hits soft 17 instead of standing | Adds about 0.2 points |
| No doubling after a split | Adds about 0.15 points |
| Doubling limited to 9, 10 and 11 | Adds about 0.1 points |
| Late surrender available | Trims a little under 0.1 points |
| Fewer decks | Lowers the edge slightly, though single-deck games usually claw it back with worse rules elsewhere |
The one to memorise is the first. A 6 to 5 table roughly triples or quadruples the cost of the game compared with a good 3 to 2 table, and it is often dressed up as a feature of a low-minimum or novelty variant. Check the payout before you sit down.
European-style tables, common online, deal the dealer's second card only after you have acted. If you double or split and the dealer then makes blackjack, you may lose the extra bets. It shifts a couple of strategy decisions against a ten or ace and adds a little to the edge.
Side bets: fun, and expensive
Perfect Pairs pays if your first two cards are a pair. 21+3 pays if your two cards and the dealer's up card make a poker-style hand such as a flush or straight. Live tables add others, such as Bust It or Hot 3.
They are popular because the payouts are large next to the even money of the main game. They are profitable for the casino because the house edge on them is typically several percent and sometimes more than ten, depending on the paytable. A small side bet on every hand can cost you more than the main game does. Play them for the occasional thrill if you like them, with money you would not miss, and know that no strategy improves them.
Software tables or live dealers?
Software blackjack, sometimes listed as RNG or "first person" blackjack, deals from a virtual deck shuffled before every hand. It is quick, minimum bets are low, and you play at your own pace, which makes it the better place to learn. UK rules require each round to take at least 5 seconds and ban autoplay, so the pace is steadier than it used to be.
Live blackjack streams a human dealer with real cards from a studio. Standard tables have seven seats, and at busy times you may wait for one, though "bet behind" lets you stake on a seated player's hand. Unlimited-seat versions get round the queue by dealing one hand that everyone plays their own way, usually at lower minimums. Live games are slower, which is no bad thing for your balance, and minimum bets tend to be higher than on software tables. Our live casino guide covers the studios and how the streams work.
Card counting, for the record, is not practical in either format. Software shuffles every hand. Live tables use eight decks and reshuffle well before the end of the shoe.
Finding a decent table
Blackjack is in every big UK lobby in both software and live form, since the casinos license from the same small group of suppliers. Rules vary by table more than by brand, so the habit worth forming is opening the help screen before your first hand: look for 3 to 2 on blackjack, dealer stands on soft 17, and doubling after splits.
For live tables we rate LeoVegas, BetMGM and Grosvenor highly, and Grosvenor is the only one of the three with bricks-and-mortar casinos across Britain behind its online tables. The full list is on our reviews page.
A practical note on bonuses: table games often count for little or nothing towards wagering requirements, and some offers exclude them outright. If you mainly play blackjack, read our wagering guide before taking a welcome offer, or skip it. And because blackjack hands come round quickly, set a deposit limit and a time reminder first. A low edge still adds up over hundreds of hands.
Next: the roulette guide, or back to all game guides.
Questions people ask
What is the house edge in blackjack?
With correct basic strategy and favourable rules it is around half a percent, among the lowest in the casino. It climbs with poorer rules, such as blackjack paying 6 to 5, and climbs a lot if you play by instinct.
Does basic strategy guarantee I will win?
No. It only reduces the house edge to its minimum. The casino still has the advantage on every hand and you should expect to lose over time.
Can you count cards in online blackjack?
Not usefully. Software blackjack shuffles the deck for every hand, and live tables use eight-deck shoes with early reshuffles or continuous shuffling machines, which removes any advantage.
Should I take insurance?
As a rule, no. Insurance is a separate side bet that the dealer has blackjack, and it carries a much higher house edge than the main game.
Do the slot stake limits apply to blackjack?
No. The 5 pound and 2 pound limits apply to online slots only. Blackjack tables set their own minimum and maximum bets, though the ban on autoplay and the minimum game speed do apply.