Every decision in blackjack has a mathematically correct answer. Hit or stand, double or split – for any combination of your hand and the dealer’s upcard, one option loses less money (or wins more) than all the others. Basic strategy is simply the complete set of these optimal decisions.

Most players rely on gut feeling. They stand on 16 because hitting feels too risky. They never split 8s against a dealer 10 because it looks like throwing money away. These instincts are wrong, and they cost real money. A player who guesses faces a house edge of 2% to 5%. A player who follows basic strategy reduces that to around 0.5%. Over thousands of hands, that difference is enormous.

What Is Basic Strategy?

Basic strategy is a set of rules that tells you the optimal action for every possible blackjack situation. It was first calculated in the 1950s by a group of mathematicians known as the “Four Horsemen of Aberdeen” and later refined by Edward Thorp using early computers.

The strategy is derived by simulating millions of blackjack hands and calculating the expected value of every possible action (hit, stand, double, split, surrender) for every combination of player hand and dealer upcard. The action with the highest expected value – or the smallest expected loss – becomes the basic strategy play.

Basic strategy is not a guarantee that you will win any individual hand. It is a guarantee that you are making the decision that loses the least money (or wins the most) in the long run. Over time, this adds up.

Why It Works

The power of basic strategy comes from one simple fact: the dealer’s upcard tells you a lot about what is likely to happen.

Dealer upcards fall into two broad categories:

• Weak upcards (2 through 6): The dealer is likely to bust. They must hit until they reach 17, and starting from a low card means drawing multiple times through the danger zone of 12-16. When the dealer is likely to bust, you should play conservatively – stand on lower totals, avoid unnecessary risk, and let the dealer break.
• Strong upcards (7 through Ace): The dealer is likely to make a strong hand (17-21). When the dealer probably will not bust, you need to take more risks to improve your own hand.

This is the core logic behind every basic strategy decision. You are not just looking at your own cards – you are responding to the dealer’s probability of busting or making a hand.

The Key Decisions

You do not need to memorize a massive chart to capture most of the value from basic strategy. The rules follow logical patterns, and understanding the reasoning makes them much easier to remember.

When to Hit or Stand on Hard Hands

Hard hands (no Ace counted as 11) are the most common situation:

The pattern is clear: against weak dealer cards (2-6), you stand on almost anything 12 or higher because the dealer is likely to bust. Against strong dealer cards (7-Ace), you keep hitting until you reach 17 because standing on a low total is almost certain to lose.

When to Hit or Stand on Soft Hands

Soft hands (containing an Ace counted as 11) are more flexible because you cannot bust on the next card:

• Soft 13-17 (A2 through A6): Hit or double. You have nothing to lose by taking a card. Double when the dealer shows 4-6 (their weakest upcards).
• Soft 18 (A7): This is the trickiest hand in blackjack. Stand against dealer 2, 7, and 8. Double against 3-6. Hit against 9, 10, and Ace. Many players always stand on 18, but against a dealer 9 or 10, your 18 is an underdog.
• Soft 19-20 (A8, A9): Always stand. These are strong hands.

When to Double Down

Doubling down means doubling your bet and receiving exactly one more card. It is your most powerful offensive weapon because it lets you get more money on the table when the odds favor you.

The general principle: double when you have a strong starting total and the dealer has a weak upcard.

• Hard 11: Double against everything. This is the best doubling hand.
• Hard 10: Double against dealer 2-9. Against 10 or Ace, just hit.
• Hard 9: Double against dealer 3-6 only.
• Soft 13-17: Double against dealer 4-6 (sometimes 3-6 depending on specific rules).
• Soft 18: Double against dealer 3-6.

A common mistake is being afraid to double. Yes, you are risking more money, but you are doing it in precisely the situations where the math is most in your favor. Not doubling when you should is one of the most expensive errors in blackjack.

When to Split Pairs

Splitting turns one hand into two, each with its own bet. The decision depends on which pair you have and what the dealer shows:

• Always split Aces and 8s. Two Aces give you two chances at 21. Two 8s make 16 (the worst hand in blackjack), but each 8 alone is a reasonable starting point.
• Never split 10s or 5s. A pair of 10s is 20 – one of the best hands possible. A pair of 5s is 10, which is a great doubling hand.
• Split 2s, 3s, 6s, 7s against dealer 2-7.
• Split 4s only against dealer 5-6 (if doubling after split is allowed).
• Split 9s against dealer 2-6 and 8-9, but stand against 7 (you already have 18, and the dealer likely has 17).

The most controversial split is 8s against a dealer 10 or Ace. It feels like you are doubling your losses. But the math is clear: playing two hands starting from 8 loses less money than playing one hand of 16. You will still lose more often than you win, but you will lose less overall.

When to Surrender

Surrender (where available) lets you forfeit half your bet instead of playing the hand. Use it sparingly:

• Hard 16 vs dealer 9, 10, or Ace: Your 16 is so weak that giving up half your bet is better than the expected outcome of playing it.
• Hard 15 vs dealer 10: Similar reasoning – you are a significant underdog.

Surrender saves roughly 0.08% on the house edge. It is a small gain, but in a game where every fraction of a percent matters, it is worth using correctly.

The Math: How Much Does Basic Strategy Save?

The numbers speak for themselves:

The “never bust” approach – standing on any hand 12 or higher – seems safe, but it is terrible. You give up so much expected value by not hitting against strong dealer upcards that the house edge actually increases compared to reasonable guessing.

Mimicking the dealer (always hitting until 17) is even worse because you do not take advantage of doubling, splitting, or the ability to stand on borderline hands when the dealer is likely to bust.

Basic strategy captures nearly all of the available edge reduction. The remaining 0.5% house edge comes from the structural advantage of the player acting first – if you bust, you lose immediately even if the dealer would have also busted.

Expected Value in Real Money

What does 0.5% house edge look like over a session?

If you play 80 hands per hour at $10 per hand, you are putting $800 per hour into action. At a 0.5% house edge, your expected loss is $4 per hour. Compare that to a 4% house edge (no strategy), where you would expect to lose $32 per hour – eight times more.

Over a 4-hour casino visit, that is the difference between an expected loss of $16 and an expected loss of $128. Basic strategy does not guarantee winning, but it dramatically reduces the cost of playing.

Common Mistakes That Cost You Money

Even players who think they know basic strategy often make these errors:

Standing on Soft 18 Against Everything

Soft 18 is a good hand, but it is not a great hand. Against a dealer 9, 10, or Ace, your 18 is an underdog. Hitting gives you a chance to improve to 19, 20, or 21. If you draw a low card and end up with a lower total, you have not lost anything – your Ace just switches from 11 to 1. Standing on soft 18 against strong dealer upcards costs roughly 0.1% in house edge.

Never Doubling on Soft Hands

Many players only double on hard 10 and 11. They miss profitable doubling opportunities on soft 13 through soft 18 against weak dealer upcards. These doubles are less dramatic but still have positive expected value.

Refusing to Split 8s Against a 10

This is the decision that feels most wrong. You have 16, the dealer is showing a 10, and basic strategy says to split – putting even more money at risk. But the math is unambiguous: two hands starting from 8 each will lose less money than one hand of 16 against a dealer 10. You are not splitting to win; you are splitting to lose less.

Taking Insurance

Insurance is offered when the dealer shows an Ace. It is a side bet that the dealer has blackjack, paying 2:1. The true odds of the dealer having a 10 in the hole are approximately 30.8% (in a 6-deck game), but the bet pays as if the odds were 33.3%. This gap gives insurance a house edge of over 7% – one of the worst bets on the table. Always decline insurance unless you are counting cards and the count is very high.

Playing Hunches Instead of Strategy

The most expensive mistake is not any single wrong decision – it is inconsistency. Following basic strategy on easy hands but going with your gut on tough ones gives back most of the edge you gained. The strategy works because it is applied to every hand without exception.

Practical Tips for Learning Basic Strategy

• Start with the hard hand rules. These cover the majority of situations you will face. Learn the pattern: stand on 13-16 against weak dealer cards, hit against strong ones.
• Learn the exceptions next. Doubling and splitting decisions build on the same logic but add more specific rules.
• Practice with free online games. Play without real money until the decisions become automatic. Several free blackjack trainers will flag when you deviate from basic strategy.
• Use a strategy card at the table. Most casinos allow players to reference a printed basic strategy card while playing. There is no penalty for using one.
• Focus on the expensive decisions first. Doubling and splitting errors cost the most because they involve extra money. Getting these right matters more than marginal hit/stand decisions.

Conclusion

Basic strategy is the foundation of smart blackjack play. It is not a secret, not complicated, and not hard to learn. It is simply the set of decisions that the math proves are optimal for every possible hand.

By following basic strategy, you reduce the house edge from as much as 5% down to roughly 0.5%. That single change transforms blackjack from a game where the casino steadily grinds away your bankroll into one where your money lasts dramatically longer and your chances of walking away ahead on any given session are close to 50%.

The skills that make you better at blackjack – calculating expected value, managing risk, and making disciplined decisions under pressure – apply directly to poker as well. If you want to develop these skills further, try the AI Poker Tools Odds Calculator to see real-time probabilities in action and build sharper card game instincts.