Online blackjack strategy: everything you need to know
Blackjack is unique among casino games. In slots, roulette, and baccarat, your decisions do not change the mathematical outcome. In blackjack, every decision matters. Hit when you should stand, and you change the expected return of the hand. This is why blackjack attracts serious players — and why basic strategy exists.
Basic strategy is not a system or a gimmick. It is the mathematically optimal play for every possible combination of your hand and the dealer’s upcard. It was calculated by running millions of simulated hands through computers in the 1950s, and it has been refined since then. Follow it, and the house edge drops to around 0.5%. Ignore it, and the house edge can climb to 2% or more.
Basic strategy fundamentals
Basic strategy tells you the correct action for every situation: hit, stand, double down, split, or surrender. The decisions depend on two pieces of information: the total value of your hand and the dealer’s face-up card.
Some of the most important rules are counterintuitive. Standing on 12 when the dealer shows a 4, 5, or 6 feels wrong because 12 is a weak hand. But the dealer is more likely to bust with those upcards, so standing is the higher expected value play. Hitting on soft 18 (Ace-7) against a dealer 9 or 10 also feels wrong, but the maths supports it.
You do not need to memorise every combination immediately. Start with the most common situations: hard totals of 12-16 against various dealer upcards. These are the hands where mistakes are most costly. Print a basic strategy chart and refer to it while you play — there is no rule against it in online blackjack.
Choosing the right blackjack variant
Not all blackjack games are created equal. The rules of each variant affect the house edge significantly:
3:2 vs 6:5 blackjack payout: This is the single most important rule. A natural blackjack paying 3:2 gives you £15 for a £10 bet. At 6:5, you get £12. That difference adds about 1.4% to the house edge. Never play 6:5 blackjack if 3:2 is available.
Dealer stands vs hits on soft 17: When the dealer stands on soft 17, the house edge is about 0.2% lower than when they hit. Always prefer games where the dealer stands on soft 17.
Number of decks: Fewer decks slightly favour the player. Single-deck blackjack has a lower base house edge than 8-deck games, assuming all other rules are equal. In online casinos, 6 or 8 decks is standard.
Doubling and splitting rules: The more flexible the rules, the better. Being able to double after splitting reduces the house edge. Being restricted to doubling only on 9, 10, or 11 increases it.
Card counting: why it does not work online
Card counting works in physical casinos because the cards are dealt from a finite shoe. As cards are removed from play, the composition of the remaining shoe changes, and a skilled counter can adjust their bets accordingly.
Online blackjack shuffles the entire shoe (or uses a continuous shuffling algorithm) after every hand. There is no shoe penetration, no running count, and no true count that means anything. Card counting is completely irrelevant to online blackjack. Anyone selling an online card counting system is selling nonsense.
Live dealer blackjack uses a physical shoe, but the penetration is typically shallow (50-60%), the minimum bets are often high, and the number of hands per hour is low. While theoretically possible, counting in live dealer games is impractical for almost everyone.
Bankroll management for blackjack
Even with perfect basic strategy, blackjack has variance. You can play correctly and still lose ten hands in a row. Your bankroll needs to withstand these swings.
A conservative guideline is to have at least 50 times your average bet as your session bankroll. If you are betting £10 per hand, bring £500 for the session. This gives you a comfortable cushion against normal variance.
Set a loss limit before you start playing. When you hit it, stop. No exceptions. The urge to chase losses is strongest in games like blackjack where you feel your decisions matter — and that feeling can lead you to play more aggressively than your bankroll supports. See our bankroll management guide for more.
Common mistakes to avoid
Taking insurance: Insurance is a side bet that the dealer has blackjack when showing an Ace. It pays 2:1, but the odds of the dealer having a 10-value card underneath are less than 1 in 3. Insurance has a house edge of about 7.7%. Never take it.
Playing 6:5 games: The convenience of a 6:5 game is never worth the 1.4% increase in house edge. Walk away.
Deviating from basic strategy based on gut feeling: “I have a feeling” is not a strategy. The maths does not care about feelings. Trust the chart.
Chasing losses by increasing bets: Progressive betting systems (Martingale, etc.) do not change the house edge. They just increase your exposure to risk. Check our house edge explainer for why these systems fail.