Guru

Most Common Blackjack Mistakes

Each point below includes the common error, the recommended correction, and a quick example spot.

Top 21 Mistakes

1
Ignoring basic strategy and playing by instinct
Correct play: Use the chart every decision until the pattern is automatic.
Why: Instinct often overweights recent outcomes and underweights long-run EV.
Common trap: A lucky hit or stand once can reinforce the wrong habit.
Example Spot
Player
10♣10
6♥6
Dealer Upcard
10♠10
2
Taking insurance too often
Correct play: Default to no insurance unless you are counting with a strong edge signal.
Why: Insurance is usually a negative-EV side bet for non-counters.
Common trap: It feels like protection, but it often costs more over time.
Example Spot
Player
9♦9
9♣9
Dealer Upcard
A♠A
3
Standing on hard 12 versus dealer 2 or 3
Correct play: Hit hard 12 against dealer 2 or 3.
Why: Dealer weak upcards 2/3 are not weak enough here to justify standing on 12.
Common trap: Players fear busting and freeze on 12.
Example Spot
Player
10♥10
2♣2
Dealer Upcard
3♦3
4
Standing on hard 16 versus dealer 7 through Ace
Correct play: Hit hard 16 against 7, 8, 9, 10, A in this ruleset.
Why: Standing lets the dealer beat 16 too often.
Common trap: 16 feels too fragile to hit, but standing is usually worse.
Example Spot
Player
10♠10
6♦6
Dealer Upcard
9♣9
5
Hitting hard 12 versus dealer 4, 5, or 6
Correct play: Stand on hard 12 against dealer 4/5/6.
Why: Dealer bust frequency is high enough that standing performs better.
Common trap: Seeing only your weak total and ignoring dealer bust pressure.
Example Spot
Player
7♠7
5♥5
Dealer Upcard
5♦5
6
Not doubling hard 11 versus dealer 2 through 10
Correct play: Double hard 11 versus dealer 2-10.
Why: 11 has strong conversion to 20/21 and benefits from bigger stake.
Common trap: Players hit to avoid risking extra money.
Example Spot
Player
6♣6
5♦5
Dealer Upcard
10♠10
7
Not doubling hard 10 versus dealer 2 through 9
Correct play: Double hard 10 versus dealer 2-9.
Why: 10 is a strong double hand when dealer upcard is not 10/A.
Common trap: Treating 10 as a generic hit hand.
Example Spot
Player
8♣8
2♥2
Dealer Upcard
6♠6
8
Not doubling hard 9 versus dealer 3 through 6
Correct play: Double hard 9 against dealer 3/4/5/6.
Why: You capture extra value while dealer is vulnerable.
Common trap: Hard 9 feels too low to invest more.
Example Spot
Player
4♣4
5♦5
Dealer Upcard
4♠4
9
Standing on soft 18 versus dealer 9, 10, or Ace
Correct play: Hit soft 18 versus 9/10/A.
Why: Dealer strength is high; passive stand underperforms.
Common trap: Soft 18 feels made, but it often needs improvement.
Example Spot
Player
A♥A
7♣7
Dealer Upcard
10♠10
10
Hitting soft 18 versus dealer 3 through 6 when double is allowed
Correct play: Double soft 18 versus dealer 3-6 (otherwise stand in some spots).
Why: Double extracts more value in high-leverage favorable spots.
Common trap: Players default to hit and miss the double window.
Example Spot
Player
A♦A
7♠7
Dealer Upcard
5♣5
11
Failing to split A,A
Correct play: Always split A,A.
Why: Two hands starting from Ace are stronger than one hard 12.
Common trap: Keeping A,A as 12 to avoid variance.
Example Spot
Player
A♠A
A♥A
Dealer Upcard
6♦6
12
Failing to split 8,8
Correct play: Always split 8,8.
Why: Hard 16 is weak; split gives two chances at better totals.
Common trap: Not wanting to commit another bet with a weak hand.
Example Spot
Player
8♠8
8♣8
Dealer Upcard
10♥10
13
Splitting 10,10
Correct play: Do not split 10,10 in this baseline strategy.
Why: 20 is already a premium made hand.
Common trap: Chasing two blackjacks instead of locking strong EV.
Example Spot
Player
10♥10
10♣10
Dealer Upcard
6♠6
14
Not splitting 9,9 versus dealer 2 through 6 or 8 through 9
Correct play: Split 9,9 against 2-6 and 8-9; stand versus 7/10/A.
Why: This split pattern captures value where dealer is not too strong.
Common trap: Applying one rule for all 9,9 spots.
Example Spot
Player
9♠9
9♦9
Dealer Upcard
8♣8
15
Not splitting 7,7 versus dealer 2 through 7
Correct play: Split 7,7 versus dealer 2-7.
Why: 14 is weak; splitting creates better expected outcomes.
Common trap: Treating all mid pairs as stand/hit hands.
Example Spot
Player
7♥7
7♣7
Dealer Upcard
6♠6
16
Not splitting 6,6 versus dealer 2 through 6
Correct play: Split 6,6 against dealer 2-6.
Why: Hard 12 is marginal; split gains EV against weak upcards.
Common trap: Avoiding split due to fear of doubling exposure.
Example Spot
Player
6♠6
6♦6
Dealer Upcard
4♣4
17
Not splitting 2,2 or 3,3 versus dealer 2 through 7
Correct play: Split these low pairs versus 2-7.
Why: Two playable hands outperform one weak total in those matchups.
Common trap: Thinking low pairs are too weak to split.
Example Spot
Player
3♥3
3♠3
Dealer Upcard
7♣7
18
Treating 5,5 as a split instead of a double hand
Correct play: Play 5,5 as hard 10, usually double versus dealer 2-9.
Why: 5,5 is a strong double setup, not a split pair.
Common trap: Seeing a pair and auto-splitting without context.
Example Spot
Player
5♥5
5♣5
Dealer Upcard
6♠6
19
Playing too fast and missing the current hand state
Correct play: Pause and confirm total, softness, and legal actions each decision.
Why: Speed increases misreads and wrong action frequency.
Common trap: Autopilot clicks after previous hand outcomes.
Example Spot
Player
A♠A
6♦6
Dealer Upcard
3♥3
20
Increasing bet size after losses without a plan
Correct play: Use a fixed bankroll plan and predefined unit sizing.
Why: Tilt-driven bet jumps increase risk of ruin.
Common trap: Trying to win losses back immediately.
Example Spot
Player
9♣9
7♠7
Dealer Upcard
10♦10
21
Confusing win percentage with expected value (EV)
Correct play: Optimize for EV, not just chance to win the hand.
Why: Some plays win less often but earn more long-term.
Common trap: Choosing the line with the highest raw win frequency.
Example Spot
Player
6♣6
5♥5
Dealer Upcard
10♠10