Card counting is a blackjack technique that tracks the ratio of high to low cards left in the shoe, so you bet more when the odds swing in your favour. It is legal in Canada and not cheating, though casinos can bar players they suspect of it. Done well it can turn a small edge, but it is difficult and rarely works online.
Card counting is the most famous way to beat blackjack, and the most misunderstood. It does not require a photographic memory, and it is not illegal. It is a disciplined method, first proven by mathematician Edward Thorp in the 1960s, for knowing when the remaining cards favour the player. This guide explains how it works, whether it is legal in Canada, if it still works online, and how realistic going pro really is. It builds on the basics in our complete guide to blackjack.
- Counting tracks high versus low cards, not every card, so you raise your bet when the deck favours you.
- It is legal in Canada and not cheating, but casinos are private businesses and can refuse service to suspected counters.
- It rarely works online, where continuous shuffling and reshuffled decks reset the count every hand.
- The edge is small and hard won, needing a big bankroll, long hours and perfect basic strategy first.
What is card counting?
Card counting is a method for tracking whether the cards still to be dealt favour the player or the dealer. High cards (tens and Aces) help the player, because they make blackjacks and strong hands more likely and cause the dealer to bust more often. Low cards help the dealer. By keeping a running tally of how many high versus low cards have already been dealt, a counter knows when the remaining shoe is rich in high cards, and bets more in those moments.
The technique was proven by mathematics professor Edward Thorp, whose 1962 book Beat the Dealer showed that the house edge could be overcome, and made card counting public. Every counting system in use today descends from his work. Counting does not tell you the next card, and it will not win every hand. It simply shifts a tiny long term edge, around one percent, from the house to a skilled player.
Is card counting illegal?
No. Card counting is legal in Canada and almost everywhere else, because you are simply using your own memory and mental arithmetic. You are not touching the cards, using a device, or altering the game, so no law is broken. Counting cards in your head is not cheating, a point the courts have upheld repeatedly.
The catch is that casinos are private businesses. They are within their rights to change the rules, shuffle more often, lower bet limits, or ask a suspected counter to leave. Online, the question is mostly academic: as covered below, the software rarely gives counting a chance to work in the first place. Using a phone app or device to help you count, however, does cross the line into cheating and is illegal.
How card counting works: the Hi-Lo system
The most popular system is Hi-Lo, and it is simpler than films make it look. Every card is worth a value of plus one, zero, or minus one. You keep a single running total as cards appear, and that number tells you whether the shoe now favours you.
- Low cards (2, 3, 4, 5, 6): count as plus one. Good for the dealer when they leave, so removing them helps you.
- Neutral cards (7, 8, 9): count as zero, no change to the count.
- High cards (10, J, Q, K, A): count as minus one. Good for you, so seeing them leave lowers the count.
Start at zero when the shoe is fresh. Add each card's value as it is dealt. A high positive running count means plenty of high cards remain, so you raise your bet. A negative count means the opposite, so you bet the minimum. Try it below.
Running count versus true count
The running count alone is not enough in a real game, because casinos deal from multiple decks. A running count of plus six means far more when one deck remains than when six decks remain. To adjust, counters calculate the true count by dividing the running count by the number of decks still in the shoe.
For example, a running count of plus six with three decks left is a true count of plus two. Bets and strategy tweaks are based on that true count, not the raw running total. It is one more layer of mental work on top of tracking every card, which is part of why counting is far harder in practice than in theory.
Can you count cards in online blackjack?
Almost never in standard online blackjack. Software games use a random number generator that effectively reshuffles the deck every hand, so the count resets constantly and never builds an advantage. There is simply nothing to track.
Live dealer blackjack is the only online format where counting is even theoretically possible, because it uses a real shoe. Even then it is impractical: studios deal from around eight decks and change the shoe at roughly half penetration, which blunts the count, and shared hand tables remove much of the edge. If your goal is a genuine edge, a land based table is the realistic setting, not a screen.
Can you make a living counting cards?
A tiny number of people do, but far fewer than the films suggest, and it is nothing like a steady salary. The edge a good counter earns is around one percent, which means the profit comes only over enormous numbers of hands, through long swings of losing sessions. A professional counter needs three things most players lack: flawless basic strategy before counting even begins, a bankroll large enough to survive the downswings, and the discipline to grind for hours without tilting.
There is also the casino side. Card counting works best as a team effort, the model made famous by the MIT Blackjack Team, precisely because a lone big bettor draws attention fast. Pit bosses watch for players who raise their bets with the count, and a suspected counter is quickly barred or shuffled out. For almost everyone, counting is best understood as a fascinating skill and a way to lower the house edge, not a career plan.
