Other Card Counting Systems – KO, Omega II, Wong Halves, and More
Note: This page is for experienced players who are familiar with the Hi-Lo system and want to understand how alternative counting systems compare. If you are new to counting, start with our Hi-Lo System guide first.
The Hi-Lo system is the most widely used card counting method, but it is far from the only one. Dozens of systems have been developed over the decades, ranging from simpler unbalanced counts designed for ease of use to complex multi-level systems engineered for maximum mathematical precision. This page covers the most well-known alternatives, what makes each one distinctive, and how they compare to Hi-Lo. For a historical overview of counting system development, Wikipedia's card counting article provides excellent background.
How Counting Systems Are Evaluated
Before comparing systems, it is worth understanding the two key metrics used to evaluate them:
| Metric | Abbreviation | What It Measures | Most Important For |
|---|---|---|---|
| Betting Correlation | BC | How well the count predicts favorable betting situations | Bet spreading — the primary source of counter edge |
| Playing Efficiency | PE | How well the count identifies strategy deviations | Index plays — a secondary source of edge |
Because bet spreading accounts for roughly 70–80% of a card counter's total edge, Betting Correlation is generally the more important metric for most players. Playing Efficiency matters more for counters who emphasize strategy deviations.
System Comparison Overview
| System | Levels | Balanced | BC | PE | Difficulty |
|---|---|---|---|---|---|
| Hi-Lo | 1 | Yes | 0.97 | 0.51 | Beginner-Intermediate |
| KO (Knock-Out) | 1 | No | 0.98 | 0.55 | Beginner |
| Red 7 | 1 | No | 0.98 | 0.54 | Beginner-Intermediate |
| Hi-Opt I | 1 | Yes | 0.88 | 0.61 | Intermediate |
| Hi-Opt II | 2 | Yes | 0.91 | 0.67 | Advanced |
| Omega II | 2 | Yes | 0.92 | 0.67 | Advanced |
| Wong Halves | 3 | Yes | 0.99 | 0.57 | Expert |
| Zen Count | 2 | Yes | 0.96 | 0.63 | Advanced |
The KO System (Knock-Out)
The KO system, developed by Olaf Vancura and Ken Fuchs and published in their 1998 book Knock-Out Blackjack, is an unbalanced single-level system specifically designed to eliminate the need for true count conversion.
KO Card Values
| Cards | KO Value |
|---|---|
| 2, 3, 4, 5, 6, 7 | +1 |
| 8, 9 | 0 |
| 10, J, Q, K, A | -1 |
The key difference from Hi-Lo: the 7 is counted as +1 in KO instead of 0. This makes the system unbalanced — a full deck counted from top to bottom does not return to 0. In a single deck, KO produces a net count of +4; in a six-deck shoe, it produces +24.
The advantage: Because the system is unbalanced, the running count itself (without true count conversion) provides usable information for betting decisions. You simply need to know the "key count" — a specific running count threshold above which you increase your bet. This eliminates the mental division step required by balanced systems.
The tradeoff: Slightly less precision than Hi-Lo in some strategy deviation scenarios, though this is a minor difference for most counters.
Best for: Players who find the true count conversion step difficult to maintain under game conditions. KO delivers most of Hi-Lo's edge with meaningfully less mental overhead.
The Red 7 System
The Red 7 system was developed by Arnold Snyder and published in his book Blackbelt in Blackjack. Like KO, it is an unbalanced system that avoids true count conversion.
Red 7 Card Values
| Cards | Red 7 Value |
|---|---|
| 2, 3, 4, 5, 6 | +1 |
| Red 7 (hearts/diamonds) | +1 |
| Black 7 (clubs/spades) | 0 |
| 8, 9 | 0 |
| 10, J, Q, K, A | -1 |
The unique feature of Red 7 is that the color of the 7 matters. Red 7s count as +1; black 7s count as 0. This creates an unbalanced count with a half-way calibrated approach between treating all 7s as neutral (Hi-Lo) and all 7s as positive (KO).
Best for: Players who want a slightly more nuanced unbalanced system with a bit more precision than KO, but still want to avoid true count conversion.
Hi-Opt I
Hi-Opt I (Highly Optimum I) is a balanced single-level system that trades Hi-Lo's betting correlation for improved playing efficiency. It was developed by Charles Einstein and refined by Lance Humble and Carl Cooper.
Hi-Opt I Card Values
| Cards | Hi-Opt I Value |
|---|---|
| 3, 4, 5, 6 | +1 |
| 2, 7, 8, 9 | 0 |
| 10, J, Q, K | -1 |
| Ace | 0 (side-counted separately) |
The Ace is counted as neutral (0) in the main count but tracked separately as a side count. This split tracking — main count plus Ace count — allows better calibration of both bet spreading and blackjack frequency, but significantly increases the mental load.
Best for: Intermediate to advanced counters who prioritize playing efficiency and strategy deviations over betting correlation, and who can handle the side count.
Omega II
Omega II is a two-level balanced system developed by Bryce Carlson and considered one of the strongest counting systems in terms of raw mathematical power.
Omega II Card Values
| Cards | Omega II Value |
|---|---|
| 2, 3, 7 | +1 |
| 4, 5, 6 | +2 |
| 8, A | 0 |
| 9 | -1 |
| 10, J, Q, K | -2 |
The two-level aspect means some cards have values of ±2 rather than ±1. This increases precision but requires faster mental arithmetic to maintain an accurate count during play.
Best for: Advanced counters willing to invest significant practice time for maximum system efficiency. Not recommended for players who have not already mastered a single-level system.
Wong Halves
Wong Halves, developed by Stanford Wong, is a three-level balanced system widely considered the most powerful single-count system available — and the most difficult to use.
Wong Halves Card Values
| Cards | Wong Halves Value |
|---|---|
| 3, 4, 6 | +1 |
| 2, 7 | +0.5 |
| 8 | 0 |
| 9 | -0.5 |
| 5 | +1.5 |
| 10, J, Q, K, A | -1 |
The use of fractional values (0.5 and 1.5) makes this system significantly harder to maintain during live play. Many practitioners double all values to work with whole numbers (+1, +2, +3, -1, -2) and then divide by 2 when calculating the true count.
With a Betting Correlation of 0.99, Wong Halves is as close to theoretically optimal as any count system gets — but the practical edge over a well-executed Hi-Lo count is marginal for most casino conditions.
Best for: Expert counters with extensive experience who have maxed out their Hi-Lo performance and want every possible edge.
Which System Should You Choose?
The answer for most people is Hi-Lo or KO:
- Hi-Lo is the best choice for the majority of counters. It is powerful, well-documented, and the system most counting coaches and books are built around. The extensive training resources available for Hi-Lo are themselves a significant advantage.
- KO is the best choice if the true count conversion step is a consistent difficulty. It gives up a minimal amount of edge in exchange for meaningfully simpler execution, and a well-executed KO count outperforms a poorly executed Hi-Lo every time.
- Omega II or Wong Halves are for expert-level players who have already mastered a simpler system and are specifically trying to extract the last decimal point of theoretical edge.
The most important factor is execution. A perfectly executed Hi-Lo count beats a sloppily executed Omega II count every session of every day. Choose the system you can maintain accurately under the distracting conditions of a real casino, and master it before considering an upgrade.