Blackjack Card Counting Guide

What is Card Counting?

Card counting is a technique where players keep track of high and low cards that have been dealt. By maintaining a running count, players can estimate the composition of the remaining deck and adjust their play and betting accordingly.

When the remaining deck is rich in high cards (10s and Aces), the player has a slight advantage. When the deck is rich in low cards, the casino has the advantage. Basic counters simply adjust their play based on this information.

The Hi-Lo Counting System

The most popular card counting system is Hi-Lo. It's simple to learn and effective:

As cards are dealt, you add or subtract based on the table above. For example:

• See a 5 dealt: Count goes +1
• See a Jack dealt: Count goes -1
• See a 7 dealt: Count stays the same (0)

A positive running count suggests more high cards remain, favoring the player. A negative count suggests more low cards remain, favoring the dealer.

Running Count vs. True Count

The running count alone isn't enough for accurate advantage estimation. You need to convert it to a true count, which accounts for remaining decks:

For example, if the running count is +12 and approximately 2 decks remain:

True Count = 12 ÷ 2 = +6

A true count of +6 means the player has a significant advantage. True count helps you:

• Adjust your betting size (bet more on high counts, less on low counts)
• Modify basic strategy slightly on very high or low counts
• Know when the game is favorable enough to play longer sessions

The Mathematics of Card Counting

Why does card counting work? Because the composition of the deck affects probabilities:

• More high cards (10, A) remaining: Player wins more blackjacks, dealer busts more often, doubling decisions become more favorable
• More low cards remaining: Dealer gets stiff hands (12-16) less often, player busts more often when hitting

Studies show that with a +1 true count, the player's advantage increases by approximately 0.5%. At a true count of +2, it's about 1% — enough to overcome the house edge and gain a slight player advantage.

Practical Considerations

Even if you understand card counting theory, practical implementation has challenges:

• Casino countermeasures: Multi-deck shoes, frequent shuffles, and surveillance make counting harder
• Bankroll requirements: You need significant capital to weather variance with advantage play
• Spread requirements: You need to vary your bets significantly, which attracts casino attention
• Emotional control: Card counting requires perfect basic strategy execution regardless of count

Most casual players benefit more from mastering basic strategy than attempting to count. The edge from perfect basic strategy (0.5%) is consistent and doesn't require a large bankroll.

Learn More

For a comprehensive understanding of blackjack advantage play, books like "Beat the Dealer" by Edward Thorp and "Blackjack Blueprint" are excellent resources. Our focus here is on understanding the mathematics and theory to become a better player overall.