The most basic and oldest card counting system is the high low count. More complicated counting systems have been devised, and many of them provide a better advantage over this system. But the high low count is probably 90% as effective as any of the more complicated systems available, and you’re less likely to make mistakes with the high-low system because it’s more straightforward and easier to use.

How Card Counting Works

All card counting systems work in the same way. They track the ratio of high cards to low cards left in the deck. High cards are more advantageous for the player, while low cards are less advantageous to the player. The reason for this is the higher chance of getting a blackjack when there are a lot of tens and aces in the deck. Since a blackjack pays out at 3 to 2, any increase in the chance of a player getting a blackjack increases the edge for the player and lowers the edge for the house.

How to Use the High Low Count

When you’re using the high low counting system, you’re going to be keeping a running count based on the cards that you see. You’re going start your count at 0, and either add 1 or subtract 1 based on the values of the cards that are dealt.

Whenever you see a 2, 3, 4, 5, or 6, you’ll add 1 to the running count.

Whenever you see a 10 or an ace, you’ll subtract 1 to the running count.

7, 8, and 9 are each worth 0. You just ignore them when you see them.

The hardest part of keeping up with the count is dealing with positive and negative numbers, but with a little practice, you’ll be able to do so easily. (My daughters used something called a “number line” to help them keep up with them. If you’re having trouble with the negative numbers, you might try counting up and down a number line, too. It won’t take you long to see how it works.)

When the count is positive, the odds are in the player’s favor. When the count is negative, the odds are in the house’s favor. The higher the positive count, the better the odds are for the player. The lower the negative count, the worse the odds are for the player.

Common sense should tell you that when you’re getting better odds, you should bet more. And that’s where the magic of the high low count comes in. You’ll raise your bets based on how high the count is. Most people use a betting spread of between 1 and 5 units, and the easiest way to raise your bet is by adding the count to 1 to determine the number of units you should bet. So if the count is +1, you’d bet two units instead of just one. If the count is +4, you’d bet five units instead of just one.

Dealing with Multiple Decks

There’s a catch though. Most casinos use multiple decks of cards. Since there are so many more cards in the deck, the effect of each card that is deal is diluted. This means that you have to convert your running count into something called a “true count.” This true count adjusts your count to compensate for the dilution factor of the multiple decks.

To get the true count, you divide the running count by the number of decks that still haven’t been played. This requires you to estimate how much of the shoe (the total number of decks) has already been dealt. It also means you have to pay attention to when the dealer shuffles the shoe—whenever the dealer shuffles, you have to start your count over.

Common sense should tell you that the deeper the dealer goes into the deck before shuffling again, the better. Dividing the running count by two decks instead of by four decks is a lot more likely to result in a positive situation for the player. So when you’re deciding at which table to play, stay away from the dealers who shuffle often, and look for the dealers who deal deeper into the deck before shuffling.

Strategy Changes

Most of the advantage from counting cards comes from resizing your bets based on the count. But some card counters want to milk every percentage point they can out of their strategies. Basic strategy for some totals changes based on the count. It’s beyond the scope of this page to explain how basic strategy changes based on the count in the high low system, but if you’re interested in getting the details, take a look at the blackjack book Sklansky on Blackjack, where he covers how to adjust your basic strategy based on the count. The last time I checked, the book was available on Amazon for less than $20