K-O System (AKA Knockout System)

Knockout System for Counting Cards in Blackjack Play

The KO System for counting cards in blackjack uses an unbalanced system to eliminate the need for converting from a running count into a true count. This makes the system as easy or easier than the Hi-Lo System. Some experts, including Norm Wattenberger of QFIT suggest that the KO System is as good as or even superior to the Hi-Lo System.

The "KO" in the name of the system actually has 2 meanings:

1It's the standard acronym for "knockout". That's a branding thing; the book Knock-Out Blackjack, features a boxing glove on the cover.)
2It's also the initials of the first names of the 2 authors responsible for popularizing this system: Ken Fuchs and Olaf Vancura.

At one point, some of the experts in the card counting community disagreed as to the effectiveness of this system. Since then, most have agreed that the K-O System is as effective as claimed.

The rest of this page explains the difference between a balanced and an unbalanced count, as well as looking at the reasons why you don't have to convert a running count into a true count using this system. We also take a look at the pros and cons of using and learning this system.

How to Count Cards Using the K-O System

If you've read our main page about counting cards or our page on the Hi-Lo System, you already understand the basics of card counting and how you can get an edge over the casino. But if you haven't, here's a quick summary and explanation.

Card counters don't memorize which cards have been played, and they're not magically able to predict what the next card out of the deck is going to be. They just track the relative ratio of high cards to low cards in the deck.

Why is this important?
It's simple, actually.

The more high cards are in the deck, the more likely it is that you'll be dealt a "natural" or a "blackjack", which pays out at 3 to 2. If you can raise your bet when you're more likely to get that increased payout, you can get an edge over the casino.

Blackjack doesn't have a large house edge to begin with, so even minor adjustments to your playing strategy can change the odds in your favor. Most card counting literature suggests that you can turn a 0.5% to 1% disadvantage into an advantage of 1% or 2%.

Over a large number of hands and with a high enough average bet, this can turn into a significant amount of money.

The first step in learning how to count cards using any system is to assign a value to each card. The K-O System is a "single level" system, which means you're only adding and subtracting 1 for each card you see. Here are the values you're going to use with the Knockout System:

  • Aces and 10s are worth -1.
  • 2s, 3s, 4s, 5s, 6s, and 7s are worth +1.
  • 8s and 9s are worth 0.
  • You'll notice that there are 20 cards worth -1, but there are 24 cards worth +1. This means that if you count through an entire deck using this count, you'll wind up with a total of +4.

    This is called an "unbalanced" system. In a balanced system, you'd wind up with a total of 0.

    The reason this system is unbalanced is because the authors wanted to find a way to eliminate the need for converting the running count into a true count. We'll cover that in more detail in the next section.

    Running Count versus True Count with the KO System

    In most card counting systems, you have to take into account the number of decks when counting. That's because with more decks in play, each card has a correspondingly lower effect on your odds.

    Here's why:

    If you deal a card worth 10 out of a single deck, you only have 15 cards worth 10 left in the deck. That's a pretty significant change.

    But if you're playing in a game with 8 decks, you'll have 127 cards worth 10 left in the deck. That's a change, but it's not nearly as significant.

    To account for this diluted effect, counters will take their running count and divide it by the number of decks left in the shoe in order to get a "true count". They then use that true count to inform their decisions about sizing their bets and changing their basic strategy decisions.

    But in the K-O System, they account for the additional decks in the shoe in 2 ways:

    1They use an unbalanced system which has more +1 value cards in it.
    2They start the count at a number determined by the number of decks in use.

    That 2nd point is important. Almost all card counting systems start at 0 and go from there, but the K-O System starts your count at a number determined by the number of decks in use, as follows:

    Deck Sizes for Card Counting with Knockout System

    You'll notice a couple of things about this. You do have more cards which can improve your count, but you need them, since the count starts so far in the hole to begin with.

    And of course, you can use this count in a single deck game, too. You just start the count at 0 like you normally would.

    Sizing Your Bets in the KO Card Counting Strategy

    Most card counters start by thinking about the size of their bankroll and how much they can afford to risk per hand. For example, if you have a bankroll of $20,000, you might be comfortable with a betting spread of $200 to $1200 per hand.

    • When the count is negative or 0, you'll bet $200 per hand.
    • When the count is +2 or higher, you'll bet $400 per hand.
    • When the count is +4 or higher, you'll bet $600 per hand.
    • And so on, up to $1200 per hand.

    Your estimated advantage when the count is positive ranges from 1% to 4%. In the hands where you're playing against a negative or 0 deck, you're still playing at a slight disadvantage to the casino (0.5% to 1%), but the increased payouts on the larger number of blackjacks makes up for this and then some when you're raising your bets.

    Important Fact

    That's where your edge comes from—getting more money on the table when you have a better chance of getting a higher payout.

    On Norm Wattenberger's site, QFIT, he offers a computer analysis of how well various counting systems correlate to increased bet sizes versus advantage and basic strategy changes. The betting correlation for this system is 0.98, which is actually higher than the betting correlation score for the Hi-Lo System. That's pretty impressive for a system that doesn't require mental division of a running count to a true count.

    The playing efficiency is also better, but it's not huge. With the Hi-Lo System, you're looking at a playing efficiency score of 0.51, versus a 0.55 for the KO System.

    The only place where KO seems to fall short is with how easy it is to use. The Hi-Lo System is slightly easier to use than the KO System, but only marginally so in our opinion. We hate long division, especially if we have to do it mentally. That's a big enough selling point that we prefer the KO System to the Hi-Lo System.


    The KO System is an excellent and effect card counting system that intermediate card counters should experiment with. It's especially good for people who have no trouble adding and subtracting, but who have trouble with mental division and estimating how many decks are left in a shoe.

    It's an unbalanced count which starts at a number other than 0, which makes it a little bit harder to learn than the Hi-Lo System, but not much. It's actually more effective than the Hi-Lo System, and if you're averse to division, then it's probably the perfect counting system for you.

    The book Knock-Out Blackjack is available on Amazon. It was published originally 20 years ago, but it's just as relevant now as it was then.

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