Blackjack Basic Strategy: The Complete Guide (And Mistakes Even Good Players Make)

Before you count cards, you need to play perfect basic strategy. A counter who makes strategy errors is leaking the edge they're trying to gain.

This guide covers basic strategy completely, explains the reasoning behind each decision, and identifies the common mistakes that even experienced players make.

What Basic Strategy Actually Is

Basic strategy is the mathematically optimal play for every hand combination, assuming you have no information about deck composition beyond the cards you can see.

It was first computed in 1956 by Roger Baldwin, Wilbert Cantey, Herbert Maisel, and James McDermott—the "Four Horsemen"—using desk calculators. They published "The Optimum Strategy in Blackjack" in the Journal of the American Statistical Association.

Since then, computers have refined the calculations to account for every rule variation. The core insight remains: for any given player hand and dealer upcard, there is exactly one decision that minimizes your expected loss (or maximizes your expected gain).

The Three Strategy Tables

Basic strategy depends on your hand type:

1. Hard hands: No Ace, or Ace counted as 1
2. Soft hands: Ace counted as 11
3. Pairs: Two cards of same value, eligible for split

Each requires different logic.

Hard Hand Strategy

Hard hands are the bread and butter of blackjack. Your decision depends on whether you might bust (totals 12+) or can't bust (totals 11 or less).

Hard Totals 17-21: Always Stand

You have a made hand. Drawing risks busting for minimal benefit. Even against a dealer 10, standing on hard 17 is correct.

Common mistake: None here—even beginners get this right.

Hard 16: The Hardest Decision

Hard 16 is the worst hand in blackjack. You'll lose more than half the time regardless of what you do.

vs. Dealer 2-6: Stand. Dealer is more likely to bust with a stiff hand.

vs. Dealer 7-A: Hit. Dealer is likely to make 17+ without busting, so you need to improve.

Common mistake: Standing against dealer 7-10 because "I'll bust if I hit." Yes, you might. But standing is mathematically worse.

Composition-dependent exception: If your 16 is made of three or more cards (like 4-5-7), you should stand against dealer 10 even before applying count adjustments. The cards you're holding have already removed small cards from the deck, slightly reducing your bust probability.

Hard 15: Similar Logic

vs. Dealer 2-6: Stand.

vs. Dealer 7-A: Hit.

Common mistake: Same as 16—fear of busting leads to incorrect stands.

Hard 13-14: Straightforward

vs. Dealer 2-6: Stand. Let the dealer bust.

vs. Dealer 7-A: Hit. You need to improve.

Hard 12: The Weird One

vs. Dealer 2-3: Hit. Dealer isn't stiff enough to rely on busting.

vs. Dealer 4-6: Stand. Dealer is very likely to bust.

vs. Dealer 7-A: Hit.

Common mistake: Standing against dealer 2-3. Players think "the dealer has a bad card." A 2 or 3 isn't that bad—the dealer will make a hand more often than you'd expect.

Hard 11: Always Double

Eleven is the best doubling hand. You can't bust, and you're likely to make 19-21.

Common mistake: Not doubling against dealer A. Some rule sets don't allow doubling against Ace, but if allowed, do it.

Hard 10: Double Against Weak Dealers

vs. Dealer 2-9: Double.

vs. Dealer 10-A: Hit. You're not favored enough to double when dealer shows strength.

Common mistake: Doubling against dealer 10 or A. The odds don't support it.

Hard 9: Selective Doubling

vs. Dealer 3-6: Double. Dealer is weak.

vs. Dealer 2, 7-A: Hit.

Common mistake: Doubling against dealer 2. The 2 isn't weak enough.

Hard 8 or Less: Always Hit

You can't bust. Take a card and reassess.

Soft Hand Strategy

Soft hands (Ace counted as 11) require different thinking. You have a "safety net"—if you draw a card that would bust you, the Ace becomes 1.

Soft 20 (A-9): Always Stand

You have 20. Don't mess with it.

Common mistake: Occasionally players double "for the action." Don't.

Soft 19 (A-8): Usually Stand

vs. Dealer 6: Double if rules allow (rare). Otherwise stand.

vs. Everything else: Stand.

Soft 18 (A-7): The Most Misplayed Hand

This is where most strategy errors happen.

vs. Dealer 2, 7, 8: Stand. You have a solid hand.

vs. Dealer 3-6: Double. Dealer is weak, and soft 18 isn't as strong as it looks.

vs. Dealer 9-A: Hit. Your 18 is likely to lose against these upcards. Try to improve.

Common mistake: Standing against dealer 9-A. "But I have 18!" Yes, and dealer showing 10 will beat your 18 roughly 60% of the time. Hitting gives you a chance to improve to 19-21.

Soft 17 (A-6): Never Stand

vs. Dealer 3-6: Double.

vs. Dealer 2, 7-A: Hit.

Soft 17 is a weak hand. Don't stand on it.

Common mistake: Standing against weak dealers. You're not giving away a made hand—17 loses to 18-21 and pushes 17. Hit or double.

Soft 16-15 (A-5, A-4): Double Against Weak Dealers

vs. Dealer 4-6: Double.

vs. Everything else: Hit.

Soft 14-13 (A-3, A-2): Very Selective Doubling

vs. Dealer 5-6: Double.

vs. Everything else: Hit.

Pair Splitting Strategy

Pairs introduce a new decision: split and play two hands. Splitting is correct when playing two hands from a split card is better than playing one hand from the paired total.

Aces: Always Split

Two hands starting with Ace are extremely valuable. You're likely to make 21 or 20.

Rule note: Most casinos only give you one card after splitting Aces.

8-8: Always Split

Sixteen is terrible. Two hands starting with 8 are much better.

Common mistake: Not splitting against dealer 10 or A. Yes, you're putting more money out against a strong dealer. But playing 16 as a single hand is worse. Trust the math.

10-10: Never Split

You have 20. Standing wins most of the time. Don't get greedy.

Common mistake: Splitting because "I want two blackjack chances." You can't get blackjack on split hands. And 20 is a great hand.

9-9: Split Against Most Dealers

vs. Dealer 2-6, 8-9: Split.

vs. Dealer 7: Stand. Your 18 beats dealer's likely 17.

vs. Dealer 10-A: Stand.

7-7: Split Against Weak Dealers

vs. Dealer 2-7: Split.

vs. Dealer 8-A: Hit.

6-6: Split Against Weaker Dealers

vs. Dealer 2-6: Split.

vs. Dealer 7-A: Hit.

5-5: Never Split

You have 10—an excellent doubling opportunity. Don't turn it into two hands starting with 5.

Common mistake: Splitting because "I'm supposed to split pairs." No—you're supposed to make the highest EV play. With 5-5, that's doubling against dealer 2-9.

4-4: Rarely Split

vs. Dealer 5-6: Split if Double After Split (DAS) is allowed.

vs. Everything else: Hit.

3-3 and 2-2: Split Against Weak Dealers

vs. Dealer 2-7: Split.

vs. Dealer 8-A: Hit.

Common Errors Summary

In order of how much they cost you:

1. Standing on soft 18 vs 9-A: Hit these.

2. Standing on 12 vs 2-3: Hit these.

3. Not splitting 8-8 vs 10 or A: Split anyway.

4. Standing on A-7 vs 3-6: Double these.

5. Doubling 11 vs A when not allowed: Know your rules—if you can't double against Ace, hit.

6. Not doubling soft hands: Players under-utilize soft doubles.

7. Taking insurance: Never (without card counting).

8. Splitting 10s: Never.

9. Standing on 16 vs 7-A: Hit these.

10. Hitting soft 17 vs 3-6: Double, don't hit.

Rule Variations That Matter

Basic strategy changes slightly based on house rules:

Dealer hits soft 17 (H17) vs. stands soft 17 (S17): H17 is worse for players. Adjustments include doubling 11 vs A (only if S17) and doubling soft 19 vs 6 (only if H17).

Double After Split (DAS) allowed: Expands the splits you should make (4-4 vs 5-6, for example).

Number of decks: Single deck changes some doubling decisions. 8+ vs A means hit in single deck, double in multi-deck.

Surrender available: Late surrender is valuable. Surrender 16 vs 9-A, surrender 15 vs 10.

Always check the rules placard before playing. A few hands into a shoe is the wrong time to discover the rules.

Why Basic Strategy Isn't Enough

Perfect basic strategy gives the house an edge of 0.4-0.6% depending on rules. That's better than almost any other casino game, but you're still expected to lose.

Card counting shifts this edge by identifying situations where the remaining deck favors the player. But counting on top of flawed basic strategy is like trying to time the stock market while making math errors in your calculations.

Master basic strategy first. Then counting amplifies your results instead of just masking your mistakes.

How to Practice

1. Flashcards: Deal yourself hands and name the correct play before looking it up.

2. Basic strategy trainers: Many free apps will drill you on decisions.

3. Casino practice: Play minimum bets with a strategy card visible (most casinos allow this). Call out your decision mentally before acting.

4. Speed drills: Once you know the strategy, drill for speed. In a real game, you have seconds to decide.

Target: 100% accuracy with instant recall. Anything less costs money.

Ready to see how strategy changes with deck composition? The calculator shows basic strategy for a neutral deck, then updates optimal decisions in real-time as cards are dealt. It's the difference between memorizing a chart and understanding why each play is correct.