Part III: Business & Regulation · Gambling Mathematics & Probability

23. Card Counting

Blackjack Math

Card counting is a technique in which a player tracks the relative proportion of high cards (tens and aces) to low cards (2s through 6s) that have been played from the shoe, allowing them to identify when the remaining undealt cards are favorable to the player. When the deck is “rich” in high cards (positive count), the player has a mathematical edge and increases their bets accordingly. When the deck is “poor” in high cards (negative count), the player minimizes wagers. Card counting is NOT illegal in most jurisdictions, but casinos reserve the right to refuse service to suspected counters. Surveillance departments train spotters to identify counting behavior through betting patterns, playing deviations, and physical tells.

In practice

A balanced counting system (like Hi-Lo) starts and ends at zero over a complete deck. Card counting typically gives the player an edge of 0.5% to 1.5% over the house when combined with proper bet sizing. Casinos counter counting through multiple decks, shallow penetration, continuous shuffle machines (CSMs), and player ejection.

One entry from the Casino Industry Glossary — 1,157 terms written for surveillance, compliance and operations professionals rather than for players. Definitions describe industry usage; where a term carries a regulatory meaning, verify against the instrument that governs your jurisdiction.