The Most Costly Errors

These mistakes are ranked roughly by how much they cost you. Fixing them starts saving you money immediately.

1. Not Using Basic Strategy

The mistake: Playing by gut feeling, hunches, or superstition instead of using the mathematically proven basic strategy chart.

The cost: Without basic strategy, the house edge is roughly 3-5%. With basic strategy, it’s approximately 0.5%. Over hundreds of hands, this difference is enormous.

The fix: Learn basic strategy. You don’t need to memorize it all at once — even learning the major rules dramatically improves your results.

2. Taking Insurance

The mistake: Placing the insurance side bet when the dealer shows an Ace.

The cost: Insurance has a house edge of roughly 7.7% with a standard shoe. It feels like “protection,” but mathematically it’s one of the worst bets on the table.

The fix: Always decline insurance. The one exception is advanced card counters who know the deck is rich in 10-value cards.

3. Standing on Soft 17

The mistake: You have Ace + 6 (soft 17) and stand, thinking 17 is a decent hand.

The cost: Soft 17 is weaker than it looks. The beauty of a soft hand is that you can’t bust by hitting. You’re giving up a free opportunity to improve.

The fix: Always hit or double down on soft 17. You’ll either improve the hand or keep the same total with a restructured hand.

4. Never Splitting 8s Against Strong Dealer Cards

The mistake: Keeping 16 because splitting 8s against a dealer 9, 10, or Ace “seems scary.”

The cost: 16 is the worst hand in blackjack. It loses more than any other hand. Two hands starting with 8 have much better prospects, even against strong dealer cards.

The fix: Always split 8s. Yes, always. Even against a dealer 10 or Ace. It’s less about winning more and more about losing less.

5. Splitting 10s

The mistake: Splitting a pair of 10-value cards because “two hands are better than one.”

The cost: A total of 20 wins the vast majority of hands. Splitting it turns one excellent hand into two mediocre ones.

The fix: Never split 10s. Stand on 20 and collect your winnings.

6. Playing 6:5 Blackjack

The mistake: Sitting down at a 6:5 blackjack table instead of a 3:2 table.

The cost: The difference is massive. On a $10 bet:

  • 3:2 pays $15 for a natural blackjack
  • 6:5 pays $12 for a natural blackjack

This single rule change increases the house edge by roughly 1.4%.

The fix: Always look for 3:2 blackjack tables. If you can only find 6:5, consider a different game.

7. Chasing Losses

The mistake: Doubling or tripling your bets after losing hands to “get even.”

The cost: You burn through your bankroll faster. Blackjack streaks are normal — both winning and losing. Increasing bets during a losing streak accelerates losses.

The fix: Keep your bets consistent. Your long-term results depend on strategy and rules, not bet sizing based on recent outcomes.

8. Not Doubling Down When You Should

The mistake: Being too conservative with double downs, especially on 11 or 10.

The cost: Double down opportunities are where a large portion of your expected profit comes from. Skipping them costs you significantly.

The fix: Double down on 11 against everything except Ace. Double 10 against 2-9. Double soft hands when appropriate.

9. Never Surrendering

The mistake: Not using surrender when it’s available, or not knowing the option exists.

The cost: In specific situations (16 vs 9/10/Ace, 15 vs 10), surrendering saves you money compared to playing the hand.

The fix: If surrender is available, use it in the correct situations. Getting back 50% of your bet is better than losing it all most of the time.

10. Blaming Other Players

The mistake: Believing that the person at third base “took the dealer’s bust card” or that bad players at your table hurt your odds.

The cost: No direct monetary cost, but it distracts you from your own strategy and creates a frustrating experience.

The fix: Mathematically, other players’ decisions have no long-term effect on your results. Focus on your own play.