Card counting: How does it work?

Blackjack has become one of the most popular games in online casinos. Given the simplicity of the game and how easy it is to learn, that is not surprising. One of the best ways of improving your chances of winning a game of blackjack online is to use a technique called card counting. While many online casinos disapprove of this technique, it is not illegal and there is nothing they can do to stop you doing it.

It is a technique that requires a decent, though not flawless, memory and a reasonable grasp of basic mathematics. That is not to say you need a degree in the subject or have to be some kind of savant genius to be able to use the technique. In fact, it is very simple to learn and use, though it does require some practice to perfect it. Read on to discover how to card count and sharpen up your chances of winning when playing blackjack online.

The four basic steps in card counting in blackjack

So where do you start when you want to learn how card counting in blackjack works? To get you started, here are the four basic steps to the process of card counting. We’ll go into more detail about these steps later on, but keep these in mind for now.

  1. You need to assign a value to each card in the deck.
  2. Ensure that you keep a running count based on the value of the last card dealt.
  3. Use this information to calculate the ‘true count’.
  4. As the count changes, alter your betting strategy.

Card counting is about knowing how many high value cards are left in the deck

Before we start looking at each of those steps in more detail, it is important to state that card counting is not a technique that requires an especially sharp memory. You do not need to be some kind of memory whizzkid to perfect this technique. You just need to have a reasonably good memory for numbers and patterns, and it is something that you can develop with practice.

The secret to successful card counting is to ensure that you maintain an accurate ratio of low value cards to high value cards that remain undealt in the deck. As a player, it is to your advantage when there are more higher value cards (those worth 10 or more, so 10s, faces and aces) left in the dealer’s deck. So what you need to make sure you keep track of, at the most basic level, is how many cards that are worth 10 or more have been dealt in the game so far.

Now we’ll look at the four stages to successful card counting in detail. They are not that hard to absorb and stick to once you know them.

Step One: Assign each card in the deck a value

To get started with card counting, the first thing that you need to do is to assign values to each card in the deck. Beginners can do this more easily by using a system called Hi-Lo. This is where you assign these values to the cards in the deck:

  • Card values two to six = +1
  • Seven to Nine = 0
  • 10 to Ace = -1

You then need to keep a close eye on each card being dealt. You keep count by adding one to the count, subtracting one or doing nothing. Each of these decisions is taken according to the values that you have assigned to each of the cards. If you keep an accurate count based on those values, then you can make a more informed decision about the size of your bets during the game.

Step Two: The running count is vital to success

Maintaining the running count at all times is really important when you are playing blackjack. If you do not do this, the whole technique will come tumbling down. Every time a card is dealt you need to adjust the count in your mind.

When your running count increases in value, the game is shifting in your favour. This should shape the way that you bet on the cards. If the reverse is happening, and the running count is decreasing in value, the dealer is beginning to gain the upper hand.

Step Three: Calculate the ‘true count’ (even when you are playing with multiple decks)

Blackjack used to be played with just one deck of cards, which made card counting a reasonably simple thing for players to do. The spread of card counting changed things somewhat, however, and many online casinos, as well as real world casinos, now operate games that use more than one deck. This makes counting the cards a little more complicated. This means that you need to keep a ‘true count’. The true count is the count per deck.

This is where you really need to concentrate. The true count is the running count divided by the number of decks that remain in the game. When your running count stands at 10, for example, with five decks left in the game, then the true count is +2. If your running count stands at a figure of -8, with two decks staying in play, then the true count is -4.

Step Four: Alter your bets as the count rises and falls

Card counting is not a technique that will win you games of blackjack on its own. Card counting provides you with the knowledge that you need to exercise your judgement more skilfully. When the count has dropped into the negative ranges or remains neutral, it is best to be cautious. As the count rises, you can be a little more flamboyant with your bets. As with all kinds of gambling, bankroll management is crucial to making card counting work for you. You should never make reckless bets that you cannot afford to lose.

This is where the memory skills that you develop by card counting need to be combined with your own betting instincts. There is not much more that you can do to develop these skills than by playing blackjack online. Play games in demo mode at your favourite online casino as this will help you become better at card counting as well as help to improve your strategic decision making during play.


Card counting is not a difficult thing to learn. The difficulty comes with perfecting the technique and putting it into practice. This is simply a matter of time and patience. The more time you put into learning the technique then the more likely you are to apply it successfully to when playing blackjack online. Always remember that casinos might not like people card counting but there is nothing they can do to stop it.

Card counting is simple to learn and very effective. While games that use more than one deck make the technique harder to deploy it is still something that anyone can learn. As with anything in gambling, the more time you take to learn and perfect the technique the more likely you are to be successful with it.