Card counting has a reputation problem. Movies portray it as a genius-level skill requiring a photographic memory and a background in mathematics. The reality is more boring and more accessible: it is a simple running arithmetic task that anyone can learn with enough practice.
The core idea
Blackjack is dealt from a shoe containing multiple decks. Once a card is dealt, it is gone until the shoe is reshuffled. This means the composition of the remaining deck changes with every hand. Card counting is a method for tracking whether the remaining deck is rich in high cards or low cards - and adjusting accordingly.
High cards (tens and aces) favor the player. They produce more Blackjacks, which pay 3:2. They are more likely to cause the dealer to bust. Some advanced plays also become more profitable when the deck is running hot.
How Hi-Lo works
The Hi-Lo system assigns a point value to every card:
- Low cards (2, 3, 4, 5, 6) = +1. These cards have left the deck, making the remaining deck slightly more favorable.
- Neutral cards (7, 8, 9) = 0. These have minimal impact on the deck composition.
- High cards (10, J, Q, K, A) = -1. These cards leaving the deck makes it less favorable.
You start with a count of zero at the beginning of the shoe. Every card you see - your cards, the dealer's card, other players' cards - gets its value added to or subtracted from your running count. A positive count means more low cards have been played, so the remaining deck is richer in high cards. That is good for you.
Running count vs. true count
The running count is just the raw total. But a count of +8 means something different in a one-deck game versus a six-deck game. To account for this, you divide the running count by the estimated number of decks remaining in the shoe. The result is the true count.
For example: running count of +8 with approximately 4 decks remaining = true count of +2. Most basic counting strategies use the true count to determine bet sizing - typically raising bets when the true count is +2 or higher.
What actually takes practice
The system is simple. The application is not. At a real Blackjack table, cards move fast. Multiple players are being dealt. You are also managing your own hand, placing bets, and trying not to look like someone who is counting cards. Keeping the count accurate through all of that is a skill that only comes from repetition.
The right way to build that skill is to practice the count in isolation first - card by card, then in groups, then at increasing speed - before trying to apply it in a full game context. Speed and accuracy both need to be there before the count becomes useful.
A realistic expectation
Card counting, done well, can shift the edge slightly in the player's favor - typically between 0.5% and 1.5% depending on the game conditions and bet spread used. That is a real advantage, but it is not a guarantee of winning any given session. Variance is high in Blackjack. The edge plays out over thousands of hands.
Also worth noting: casinos are well aware of card counting and are within their rights to ask counters to leave. Counting is not illegal, but it is unwelcome.
