Blackjack is the casino table game with the lowest house edge available to the average player — but only if you play correctly. With basic strategy applied consistently, the house edge in a standard six-deck UK blackjack game falls to between 0.4% and 0.6%. Without it, errors in decision-making can push that edge above 2%, costing you significantly more over time. This guide explains what basic strategy is, how it was developed, and how to apply it at the table.
What Is Basic Strategy?
Basic strategy is a mathematically derived set of decisions that tells you the optimal play for every possible combination of your hand and the dealer's upcard. It was first developed in the 1950s using computing power to calculate expected values for every scenario across millions of simulated hands. The strategy is not a guess or a heuristic — it is the provably correct play for each situation, assuming a standard game with known rules.
Basic strategy does not guarantee you will win any individual hand. What it does is minimise the house's mathematical advantage over time, so that over thousands of hands you lose as little as possible to the built-in edge.
The Core Rules of UK Blackjack
Before applying basic strategy, confirm the rules at your chosen table, as variations affect the correct decisions:
- Number of decks: typically six or eight at online UK casinos.
- Dealer stands or hits on soft 17: standing is player-friendly.
- Blackjack pays 3:2 (standard) or 6:5 (avoid this variant — it raises the house edge by 1.4%).
- Doubling down: most tables allow on any two cards.
- Splitting: pairs can usually be re-split up to four hands.
- Surrender: rarely available online but worth seeking out.
Hard Hands
A hard hand is any hand without an ace counted as 11, or one where the ace must be counted as 1 to avoid busting.
Hard 8 or Below
Always hit. Your total is too low to stand, and you cannot bust.
Hard 9
Double down if the dealer shows 3, 4, 5, or 6. Otherwise hit.
Hard 10 or 11
Double down when your total beats the dealer's upcard. Specifically:
- Hard 10: double against dealer 2 through 9; hit against 10 or ace.
- Hard 11: double against dealer 2 through 10; hit against an ace.
Hard 12
Stand if the dealer shows 4, 5, or 6 (dealer is likely to bust). Hit in all other cases.
Hard 13 to 16
Stand when the dealer shows 2 through 6. Hit against 7 through ace. These are the most difficult hands in blackjack because your chance of busting on a hit is high, but standing against a strong dealer card is also unfavourable.
Hard 17 or Above
Always stand. Never hit a hard 17 or higher — the risk of busting is too great.
Soft Hands
A soft hand contains an ace counted as 11. It cannot bust on a single hit, which is why soft hand strategy differs from hard hand strategy.
Soft 13 and 14 (Ace-2, Ace-3)
Double against dealer 5 or 6. Otherwise hit.
Soft 15 and 16 (Ace-4, Ace-5)
Double against dealer 4, 5, or 6. Otherwise hit.
Soft 17 (Ace-6)
Double against dealer 3 through 6. Otherwise hit. Never stand on soft 17.
Soft 18 (Ace-7)
Stand against dealer 2, 7, or 8. Double against dealer 3 through 6. Hit against dealer 9, 10, or ace. Many players make the mistake of always standing on soft 18 — it is actually a hand with specific doubling opportunities.
Soft 19 and 20 (Ace-8, Ace-9)
Always stand.
Pairs
When you are dealt two cards of equal value, you have the option to split them into two separate hands.
- Aces: always split. You receive one additional card on each ace and cannot re-hit.
- Eights: always split. A hard 16 is one of the worst hands in the game, and splitting gives two chances to improve.
- Tens: never split. A total of 20 is a near-certain winner — do not break it up.
- Fives: never split. Treat a pair of fives as a hard 10 and apply doubling rules.
- Fours: split against dealer 5 or 6 only. Otherwise hit.
- Twos and threes: split against dealer 2 through 7. Otherwise hit.
- Sixes: split against dealer 2 through 6. Otherwise hit.
- Sevens: split against dealer 2 through 7. Otherwise hit.
- Nines: split against dealer 2 through 6 and 8 or 9. Stand against dealer 7, 10, or ace.
Surrender
If surrender is available, use it on hard 15 against a dealer 10, and hard 16 against dealer 9, 10, or ace. Surrendering returns half your stake — a better outcome than playing a hand with a very high expected loss.
Using a Strategy Card
Basic strategy is not something most players memorise immediately. At a live casino table, using a printed strategy card is permitted in the UK and most jurisdictions. Online, you can keep a chart open in a second tab. Consulting the chart on every hand is not a sign of weakness — it is the correct approach to minimise errors.
After playing a few hundred online sessions with the chart in view, many players find they have internalised the main decision points without consciously memorising them.
How Much Does Basic Strategy Save?
The difference between optimal and poor play is significant. A player making common intuitive mistakes — standing on soft 18 against a 9, not splitting aces, hitting hard 12 against a dealer 4 — might face a house edge of 2% to 4%. With correct basic strategy on a standard six-deck game where the dealer stands on soft 17, that edge falls to approximately 0.5%.
On a session of 200 hands at £5 per hand (£1,000 total wagered), the difference in expected loss between a 2% edge and a 0.5% edge is:
- At 2%: expected loss of £20.
- At 0.5%: expected loss of £5.
Over a year of regular play that gap compounds into hundreds of pounds.
Common Mistakes to Avoid
- Taking insurance: insurance is a side bet that the dealer has blackjack. The house edge on insurance is approximately 7.7% — never take it.
- Not doubling when correct: players often fear doubling because it puts more money at risk, but the mathematics clearly favour it in the correct situations.
- Splitting tens: a total of 20 wins the majority of the time. There is no reason to break it.
- Hitting hard 12 against dealer 4, 5, or 6: the dealer has a high chance of busting; give them the opportunity.
Conclusion
Basic strategy is the foundation of intelligent blackjack play. It will not turn a losing game into a winning one — the house edge, however small, is always present. But it is the single most effective tool a player has for stretching their bankroll, extending their enjoyment, and playing the game the way the mathematics intend. Learn it, use it, and revisit it any time you sit down at a blackjack table.