The Hi-Lo card counting system

The value table

Hi-Lo is a balanced, level-one count designed by Harvey Dubner in 1963 and popularised by Edward Thorp's second edition of Beat the Dealer. Every card in the deck gets exactly one of three tags.

• Plus one: 2, 3, 4, 5, 6.
• Zero: 7, 8, 9.
• Minus one: 10, J, Q, K, A.

A single deck contains twenty cards that count plus one (four each of five ranks), twelve that count zero, and twenty that count minus one (four tens, four jacks, four queens, four kings, four aces). Twenty plus and twenty minus net to zero, which is why Hi-Lo is called balanced. If you tag every card in a fresh six-deck shoe correctly, the running count at the burn card should be exactly zero. The most useful self-check in the whole system is to count down a deck against a stopwatch at home and verify it lands on zero.

What the count means

The count is a snapshot of the shoe's composition relative to a fresh deck. Positive means more small cards have left and the remaining shoe is rich in tens and aces. Negative means the opposite. The practical effects of a tens-rich shoe are favourable to the player. Naturals come more often (the player gets paid three-to-two and the dealer is just paid even money). Doubling-down hands win more often because tens are more likely to land on the eleven or ten that the player just doubled on. The dealer busts more often, because the forced-hit rule on sixteens has more tens to bust against. None of these effects are dramatic. Added up across thousands of hands they produce the player edge that counting depends on.

Why Hi-Lo and not something stronger

Card-counting research has produced systems with higher theoretical efficiency than Hi-Lo. Hi-Opt II is a level-two count that assigns weights of plus two to 4s and 5s, and tracks aces separately. Zen is another popular level-two system. Both extract more edge per hand on paper.

In practice, the win comes from execution. A level-two count is twice as cognitively expensive to keep at table speed, and a single mis-tag of a five or four can put the running count off by two instead of one. Hi-Lo is forgiving enough that an attentive amateur can keep it correctly through a six-deck shoe at a real casino pace. That is the reason Hi-Lo remains the most-played count in the world. A perfectly executed Hi-Lo session is worth substantially more than a sloppy Hi-Opt II session.

The trade-off Hi-Lo makes is around aces. Aces count minus one, like any other ten-value card, which costs Hi-Lo some accuracy on insurance and bet-sizing decisions where the remaining ace density matters distinctly. Side-counting aces is a common upgrade that professional Hi-Lo players adopt after they have the base system automatic. We do not recommend trying it until the base count is truly automatic.

How fast you need to be

At a six-deck shoe with seventy-five percent penetration, you will see roughly 250 cards before the cut. A typical heads-up table runs about three hands a minute, or six cards a minute including dealer upcards plus your hand. Multi-player tables go slower. You need to tag every card the dealer turns over, including the dealer's hole card when it gets revealed, and the bust cards on hits.

The minimum speed you need before you have any business playing for money is roughly a deck of cards in under thirty seconds, while keeping running count accurate to zero at the end. Most players need weeks of daily drilling to get there. The Hi-Lo trainer is the cheapest way we know of to log those repetitions.

The handoff to true count

The running count is a number, but the betting decision depends on how much shoe is left. A plus six in the first deck of a six-deck shoe is weak. A plus six in the last deck is enormous. The conversion that normalises the running count for shoe depth is the true count, which gets its own write-up at True count, explained. Hi-Lo only becomes a betting system once the true count is in your hands.