Hi-Lo card counting

The Hi-Lo values

The best known and most used method is the Hi-Lo system. Every card that comes out of the shoe gets a value of +1, 0 or −1.

+1, the low cards: 2, 3, 4, 5 and 6. When they fall, fewer low cards are left. That is good for the player. 0, the neutral cards: 7, 8 and 9. They have no influence on the edge and do not change the count. −1, the high cards: 10, jack, queen, king and ace. When they fall, the chance of a blackjack or a high starting hand for the player goes down.

A deck has 20 low cards and 20 high cards, so its 52 cards add up to exactly 0. That makes Hi-Lo a balanced count: after the last card of the shoe the count is back at 0.

Step by step

1. Start the count: begin at 0 as soon as the dealer has shuffled and starts to deal. 2. Keep the running count: add up the values of all the cards that are turned face up on the table, all the time. 3. Work out the true count: casinos play with several decks, so divide the running count by the estimated number of decks still in the shoe. True count = running count ÷ decks left. 4. Adjust your bet: the higher the true count, the bigger your edge. Bet more when the count is positive, and bet the minimum, or sit out, when it is negative.

Why the true count

A running count of +6 means something different at the start of a six-deck shoe than near its end. With five decks left, six extra high cards are spread over 260 cards and hardly matter: the true count is +1.2. With one deck left the same six cards make a true count of +6, a big edge. Counters estimate the decks left by looking at the discard tray, usually to the nearest half deck. The app shows the tray and the shoe with a tick for every deck, and the division under the true count.

Why tens and aces help the player

A blackjack, an ace with a ten, pays the player 3 to 2, but when the dealer has one the player only loses the bet. More tens and aces also make the dealer bust more often, because the dealer must keep drawing until 17, while the player may stand on 12. Doubling down on 10 or 11 wins more often too. Low cards do the opposite: they help the dealer reach 17 to 21 without busting.

How big the edge is

With six decks, the dealer standing on all 17s, doubling after a split and blackjack paying 3 to 2, a player using basic strategy and betting the same every round loses about 0.4% of the money bet. Each point of true count adds roughly 0.5%, so the player has the edge from a true count of about +1. That is not often: with six decks the true count is +2 or more in only about one round in seven. Betting 1 unit at low counts and up to 12 at high counts, and sitting out below −1, turns this into a profit of about 1% of the money bet in the app's simulation. The swings are much larger than the edge, so a counter needs a big bankroll and many hours of play.

Penetration, live casinos and online games

The deeper the dealer deals into the shoe before shuffling, the higher the true counts can climb. This is called penetration. In regular online blackjack counting is impossible, because the software shuffles the cards digitally after every hand: the count is 0 before every bet. At live casino tables, with a real dealer on a video stream, it is sometimes possible, but they often shuffle as soon as half the shoe has been dealt. That poor penetration keeps the edge small: in the app's simulation, a six-deck shoe shuffled halfway leaves the counter less than a third of the edge of a shoe dealt to 75%.

Is it legal?

Yes. Counting cards with your own head is not illegal. Casinos are private property, though, and have the right to refuse players or to ask them to stop if they suspect that they are counting cards. Using a device or software to help you count at a real table is illegal in many places.

A short history

In 1962 the mathematician Edward Thorp published Beat the Dealer, which showed with computer calculations that blackjack can be beaten by keeping track of the cards. His first method counted tens. In 1963 Harvey Dubner proposed the simpler high-low count, and in 1975 Stanford Wong described it in detail in Professional Blackjack. Hi-Lo is still the count most players learn first: it is easy to keep, and more complex counts gain only a little.

Explore it in PictorX

Open Hi-Lo card counting and a blackjack table deals by itself, a card at a time. Every card shows its value, the running count is on the left under the discard tray, and the true count is on the right under the shoe. The chart follows the count through the shoe up to the cut card. In Practice the values and counts are hidden and after every round you pick the running count. Count down a deck turns 52 cards one by one; with one card left the count tells you what it is. Deal a million rounds to see the edge at each true count, compare a flat bet with betting by the count, and try a live casino that shuffles halfway or an online game that shuffles after every round.