Blackjack is straightforward to learn, but many players make recurring mistakes that cost them money. These errors range from basic strategy violations to misunderstanding how the game works. Even experienced players sometimes fall into bad habits. The good news is that most mistakes are easy to fix once you recognize them. Avoiding these common errors can reduce the house edge significantly and improve your overall experience at the table. This guide covers the most frequent blackjack mistakes, explains why they're problematic, and shows you how to correct them. Whether you're a beginner or have played for years, reviewing these pitfalls helps you play smarter and more efficiently.
Mistake 1: Taking Insurance
Insurance is offered when the dealer shows an Ace. It's a side bet that costs half your original bet and pays 2:1 if the dealer has blackjack.
Why it's a mistake:Insurance is mathematically unfavorable. The dealer has a blackjack roughly 30.8% of the time, but insurance pays as if it happens 33.3% of the time. Over time, this bet loses you money.
The math:You're betting at 2:1 odds on an event that happens less than one-third of the time. Unless you're counting cards and know the remaining deck is rich in 10s, insurance is a bad bet.
What to do instead:Always decline insurance. Even when you have blackjack and are offered "even money" (which is mathematically identical to insurance), decline and take your chances.
Mistake 2: Playing 6:5 Blackjack Tables
Some casinos offer blackjack tables that pay 6:5 instead of the standard 3:2 for natural blackjack.
Why it's a mistake:This rule change increases the house edge by approximately 1.4%. It dramatically reduces your expected return.
The difference:- 3:2 payout: $10 bet wins $15 on blackjack - 6:5 payout: $10 bet wins $12 on blackjack
What to do instead:Always check the blackjack payout before sitting down. If a table pays 6:5, find a different table or casino. This is one of the worst rule variations you can encounter. For more on how rules affect your odds, see our guide on [house edge in blackjack](#).
Mistake 3: Mimicking the Dealer's Strategy
Some players think they should copy the dealer's strategy: hit on 16 or less, stand on 17 or more.
Why it's a mistake:The dealer plays last, which gives them a massive advantage. When you bust, you lose immediately — even if the dealer later busts too. This advantage doesn't exist if you copy the dealer's strategy. Copying the dealer increases the house edge to around 5-6%, compared to 0.5% with basic strategy.
What to do instead:Use basic strategy, which accounts for the dealer's upcard and your hand. For example, basic strategy tells you to stand on 12-16 when the dealer shows 2-6 (hoping they bust), while the dealer would hit these totals.
Mistake 4: Never Splitting or Doubling
Some players avoid splitting and doubling because they don't want to put more money at risk.
Why it's a mistake:Splitting and doubling are essential parts of optimal strategy. They let you increase bets in favorable situations and turn bad hands (like 16) into playable ones (like two 8s). By never splitting Aces or 8s, or never doubling on 10 or 11, you're giving up significant expected value.
What to do instead:Learn when to split and double. Start with these basics: - Always split Aces and 8s - Never split 10s or 5s - Double on 10-11 vs weak dealer cards For detailed strategy, see our [blackjack strategy guide](#).
Mistake 5: Splitting 10s
On the opposite end, some players split 10s thinking they can make two strong hands.
Why it's a mistake:You already have 20, one of the best possible hands. Splitting breaks up a near-certain winner into two hands that start with 10 — good, but not as good as 20. The math overwhelmingly favors standing on 20.
What to do instead:Never split 10s, no matter what the dealer shows. Stand and collect your likely win.
Mistake 6: Playing Side Bets
Many blackjack tables offer side bets like "Perfect Pairs," "21+3," or "Lucky Ladies."
Why it's a mistake:Side bets have much higher house edges than the main game — typically 3-10% or more. They're designed to look exciting but are mathematically poor bets.
Example house edges:- Perfect Pairs: 3-6% - 21+3: 3-7% - Insurance (technically a side bet): 7%
What to do instead:Stick to the main blackjack game. If you want variety, choose a different table game rather than taking side bets with terrible odds.
Mistake 7: Increasing Bets After Losses (Martingale System)
Some players double their bet after every loss, thinking they'll eventually win and recover all losses.
Why it's a mistake:This is called the Martingale system, and it doesn't work. You'll hit either your bankroll limit or the table maximum before recovering losses. One long losing streak can wipe out your entire session budget.
Example:Start with $10. After five consecutive losses (not uncommon), you'd need to bet $320 on the sixth hand. Many tables have maximums of $500, preventing further doubling.
What to do instead:Use flat betting (same bet every hand) or small, controlled bet adjustments. Never chase losses by dramatically increasing bets.
Mistake 8: Not Learning Basic Strategy
Many players rely on hunches, feelings, or "gut instinct" instead of using mathematically optimal strategy.
Why it's a mistake:Basic strategy is proven through millions of computer-simulated hands. Your hunches don't change the underlying probability. Playing without strategy increases the house edge from 0.5% to 2-4% or higher.
What to do instead:Learn basic strategy gradually. Start with the core rules (hit on 11 or less, stand on 17+, understand dealer upcard impact) and build from there. You can use strategy charts while playing online, and many casinos allow discreet reference cards at physical tables.
Mistake 9: Sitting at the Third Base Seat If You're a Beginner
"Third base" is the seat immediately to the dealer's right — the last player to act before the dealer.
Why it's sometimes a mistake:Some players (incorrectly) believe the third base player affects everyone's outcome. If you're a beginner and make strategy errors, other players might blame you for "taking the dealer's bust card." This is superstition — your decisions don't actually affect other players' long-term odds — but it can create an uncomfortable environment.
What to do instead:Sit anywhere you're comfortable. If you're worried about other players' reactions, choose a seat in the middle or far left. But know that third base has no real mathematical impact on others.
Mistake 10: Not Setting a Stop-Loss
Many players continue playing after significant losses, hoping to win back their money.
Why it's a mistake:Chasing losses usually leads to bigger losses. The house edge doesn't change just because you're losing — continuing to play means accepting more expected loss.
What to do instead:Set a stop-loss before you play. Decide how much you're willing to lose in a session and stop when you reach that limit. This is a bankroll management fundamental. For more on safe play, see our guide on [responsible gambling tools](#).
Mistake 11: Drinking Too Much While Playing
Casinos often offer free drinks at the tables, which seems generous.
Why it's a mistake:Alcohol impairs judgment and slows decision-making. You're more likely to deviate from basic strategy, make impulsive bets, or play longer than planned. Casinos offer free drinks because intoxicated players make more mistakes and lose more money.
What to do instead:Limit alcohol consumption while playing, especially if you're playing with significant money. Drink water between alcoholic drinks or save drinking for after you're done playing.
Mistake 12: Ignoring Table Rules and Conditions
Not all blackjack games have the same rules. Players sometimes sit down without checking the conditions.
Rules that significantly affect house edge:- Blackjack payout (3:2 vs 6:5) - Dealer hits or stands on soft 17 - Number of decks - Doubling restrictions - Surrender availability
What to do instead:Check table rules before playing. Look for signs posted at the table or ask the dealer. Choose tables with player-friendly rules when possible.
Mistake 13: Playing When Tired or Emotional
Playing blackjack while tired, upset, or emotional leads to poor decisions.
Why it's a mistake:Basic strategy requires focus and discipline. When you're tired or emotional, you're more likely to make errors, play too long, or bet more than you planned.
What to do instead:Only play when you're alert and in a good mental state. If you're having a bad day or feeling tired, take a break or skip playing altogether.
Mistake 14: Believing in "Hot" and "Cold" Tables or Dealers
Some players think certain tables, dealers, or seats are "hot" (winning) or "cold" (losing).
Why it's a mistake:Each hand is independent. Past results don't influence future outcomes. The cards don't "remember" previous hands. Moving to a different table or seat doesn't change the mathematical probabilities.
What to do instead:Choose tables based on rules and conditions, not recent results. Focus on playing optimal strategy rather than searching for patterns that don't exist.