How to Count Cards in Blackjack: Step-by-Step Guide

Contrary to Hollywood portrayals in movies like 21 or Rain Man, card counting is neither photographic memory nor illegal wizardry. It is straightforward probability mathematics applied systematically.

In blackjack, past cards directly influence future cards because dealt cards are not reshuffled immediately. When small cards (2 through 6) leave the shoe, the remaining cards are disproportionately rich in 10-value cards and Aces. This fundamentally shifts the mathematical advantage from the casino to the player.

Why High Cards Favor the Player

A shoe rich in 10s and Aces benefits the player in three decisive ways:

1. Natural Blackjacks (3:2 Payout): Both the dealer and player receive blackjacks more frequently. However, players receive a 3:2 bonus (150% payout) on blackjacks, whereas dealer blackjacks only forfeit the player's original bet.
2. Dealer Busts: The dealer is bound by rigid house rules to hit hands totaling 16 or less. In a 10-rich deck, the dealer will bust far more often.
3. Double Downs Succeed: Players can double down on 9, 10, and 11, drawing high cards with much greater frequency.

Step 1: Assign Point Values to Cards

Card counting does not require memorizing individual cards. Instead, you assign point values to groups of cards. In systems like Wong Halves (or basic Hi-Lo), low cards are positive (+), neutral cards are zero, and high cards are negative (-):

• Cards 2, 7: +0.5
• Cards 3, 4, 6: +1.0
• Card 5: +1.5 (the biggest dealer savior)
• Card 8: 0.0 (neutral)
• Card 9: -0.5
• Cards 10, J, Q, K, A: -1.0

Step 2: Maintain a Running Count (RC)

As the round begins, your count starts at 0. As each card is dealt across the table, add or subtract its value to your mental running tally. If cards dealt are [5 (+1.5), King (-1.0), 3 (+1.0), 10 (-1.0)], your running count is +0.5.

Step 3: Convert to True Count (TC) in Multi-Deck Shoes

A running count of +6 in a single-deck game is astronomical; in an 8-deck shoe with 7 decks remaining, it is negligible. To measure true card concentration, divide the Running Count by the number of remaining decks:

Step 4: Bet Spreading & The Kelly Criterion

Card counters do not bet the same amount on every hand. When the True Count is neutral or negative (TC ≤ +1), you bet the table minimum (1 unit). When the True Count rises above +2, the house edge disappears and the player gains an advantage of approximately 0.5% per True Count point.

Is Card Counting Legal?

Yes. Card counting using your brain is completely legal under US federal and state laws, as well as European gaming jurisdictions. Casinos are private businesses, however, and reserve the right to refuse service or ask advantage players to play games other than blackjack ("backing off").