What is card counting in blackjack?
Last updated:
Card counting is a technique where players track the ratio of high cards to low cards remaining in the shoe. When the deck is rich in high cards the player has a statistical edge, so counters increase their bet size in those situations and bet smaller when the deck favors the house.
How it works
The most widely known system is Hi-Lo. Each card dealt is assigned a value: 2-6 add +1 to the running count, 7-9 are neutral, and 10-A subtract 1. A high positive count means more high cards remain, which favors the player. Counters divide the running count by the number of decks remaining to get the ‘true count’ which guides bet sizing.
Is it allowed?
Card counting is not illegal but casinos actively discourage it. If a casino suspects you are counting they can ask you to stop playing blackjack, limit your bet spreads, or ban you from the property. Online blackjack using continuous shuffle machines is immune to counting since the deck is reshuffled after every hand. Live dealer online blackjack uses real decks but the penetration (how much of the shoe is dealt before reshuffling) is typically shallow, limiting any advantage.
Ben Barber got into the gambling industry through the poker rooms of London in the early 2000s. After building up a solid grounding in casino, sports betting and poker, he made the move to Malta where he spent close to a decade writing for some of the biggest affiliate networks in the region. A few years ago he relocated to Bali, which shifted his focus toward website strategy and affiliate marketing. The casino side never really left, though. He still writes reviews, how-to guides and in-depth pieces on everything from slots and live dealer tables to crypto casinos and sweepstakes sites. His approach is fact-first: help players understand how online gambling actually works before they deposit a cent.