How to count cards in blackjack

Why counting cards works

Blackjack is one of the only casino games where the cards you have seen change the math of the cards you are about to see. The shoe is a finite stack. When small cards have come out at a higher rate than the deck composition expects, the cards left behind are richer in tens and aces. Tens and aces are the cards that pay you three-to-two on a natural and give the dealer the most bust outs. A counter does nothing more sophisticated than track that imbalance and bet bigger when the remaining shoe is on the player's side.

The house edge against a basic strategy player on a typical six-deck S17 DAS table is about 0.43 percent. A well-executed Hi-Lo count with a 1-to-8 bet spread on the same table flips that into roughly a 0.5 to 1 percent advantage for the player. It is not glamorous money, and it is not guaranteed money. It is enough to be worth doing if the rules are right and the heat is tolerable.

The four things a counter has to do

Every counting workflow, from the simplest Hi-Lo system to advanced multi-parameter counts, decomposes into the same four steps. If any single step breaks down at the table, the edge evaporates.

1. Keep a running count. Every card that comes out of the shoe gets tagged plus one, zero, or minus one depending on its rank, and added to the running tally. The whole shoe should balance to zero. If it does not, you missed a card.
2. Convert to a true count. The running count is only useful relative to how much shoe is left. A plus six in the first deck of an eight-deck shoe is barely anything. A plus six with one deck left is enormous. Dividing the running count by decks remaining gives the true count, which is what the bet ramp keys off.
3. Vary the bet. Bet the minimum when the true count is neutral or against you. Push more units out at higher true counts on a pre-agreed ramp like 1-2-4-6-8. Without bet variation, the edge stays theoretical.
4. Deviate on the high counts. Take insurance at true count plus three. Stand on sixteen against a ten at plus zero or higher. The full table lives in the Illustrious 18 and Fab 4. Each play is worth a fraction of a percent on its own; together they are a meaningful chunk of the edge.

Why this is harder than it sounds

The math is high-school arithmetic. The execution is the hard part. The dealer pitches cards at a rate that does not wait for you. Other players make slow decisions that scramble your concentration. The pit watches large bet variations carefully and is paid to identify counters. Casinos have made the conditions worse over the last twenty years: six- and eight-deck shoes, shorter penetration, six-to-five naturals, continuous shufflers. Card counting still works on the tables that have not been gutted, but those tables are scarcer than they used to be.

The skill that separates a profitable counter from a hobbyist is not knowledge. It is reliability. Counting accurately for six straight hours under pressure, while playing perfect basic strategy and the correct deviations, while varying your bet on a schedule that does not attract heat. That kind of reliability does not come from reading. It comes from drilling on a real table, at real speed, with feedback after every hand. Which is what the rest of this site is for.

What to learn next

The Hi-Lo system is the system to learn first. It is the easiest count to keep accurate at table speed and has the most published material to cross-reference. Read The Hi-Lo card counting system for the value table and the reasoning behind it, then True count, explained to understand the divide step, and finally How to size your bets to set the ramp.