Part III: Business & Regulation · Gambling Mathematics & Probability

30. KO System (Knockout System)

Blackjack Math

The KO System, short for Knockout, is an unbalanced, single-level card counting system that eliminates the need for true count conversion by using a non-zero Initial Running Count (IRC). In the KO system, 2-7 are counted as +1, 8-9 as 0, and 10-Ace as -1, creating an imbalance of four more positive than negative values per deck. Players simply compare the running count to a predetermined key count (which varies by number of decks) to determine when to increase bets. The KO system’s primary advantage is simplicity — it avoids the mental division required for true count conversion. It has a betting correlation of 0.98 and playing efficiency of 0.55, making it nearly as effective as Hi-Lo while being easier to execute.

In practice

Because KO is unbalanced, the running count at the end of a shoe will equal the number of decks played multiplied by 4 (the imbalance per deck). The key count for a six-deck game is typically +4. KO is particularly popular among recreational advantage players and team play scenarios.

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