Learn Card CountingWhat is card counting?
Updated
The big idea
Blackjack is a game with memory. Every card dealt is removed from the shoe, so the cards that remain are slightly different from the ones you started with. A roulette wheel has no such memory: a red spin doesn’t change the odds of the next spin. In blackjack, if a lot of low cards (2 through 6) have come out, the remaining cards are richer in tens and aces.
That matters because tens and aces help the player more than the dealer. Tens and aces give you more blackjacks (which pay 3:2 for you, but the dealer gets no bonus), they make the dealer bust more often when forced to hit stiff hands, and they make doubling down and splitting more profitable. Low cards do the opposite: they help the dealer finish hands.
Card counting is a simple bookkeeping system for noticing when the shoe is rich in high cards. When it is, you bet more. When it isn’t, you bet the minimum (or sit out). That’s all it is.
How a count works
You don’t memorize which cards are gone. Instead you assign every card a small number, called its tag, and keep a single running total. In the popular Hi-Lo system, low cards are +1, middle cards are 0, and tens and aces are −1. Watch this short sequence:
The running count after six cards is +1: a little more low cards than high ones have been used, so the cards left are very slightly richer in tens and aces. Over a whole shoe the tags cancel out to zero, which is why the count is a relative measure of how the remaining cards lean.
Why it gives you an edge
With good rules and perfect basic strategy, the house still has a small advantage, typically around half a percent. Counting lets you spot moments when that advantage flips. At a high count the player may have an edge of one percent or more, and you can bet more at those moments and the minimum at the others. Your average edge across all hands is still small, often well under one percent, because most hands are not favorable.
You also use the count to make slightly different playing decisions in certain spots (for example, taking insurance when the count is high enough). Those adjustments are a smaller source of profit than betting more at the right times, and you don’t need them to begin.
What counting can’t do
Be honest with yourself about the limits:
- It doesn’t predict the next card. A high count means the odds are better, not that the next card is a ten. You will still lose many hands at high counts.
- The edge is thin. Variance dominates. A good counter can easily be down for days or even weeks.
- It needs favorable conditions. Deep penetration (many cards dealt before the shuffle), decent rules (3:2 blackjack payouts, the dealer standing on soft 17), and enough decks to see a real spread all matter. Automatic shufflers that reshuffle every hand make counting pointless.
- It takes effort. Counting while making decisions, talking, and managing money is harder than counting flash cards on your couch.
Realistic expectations
Here’s an illustration with round numbers. Say you bet $10 at low counts and spread up to $100 at high ones, averaging roughly $30 a hand over about 70 hands an hour. At an average edge of around 0.7%, your expected profit is about $15 an hour. But the swings are huge: the typical one-hour result can be several hundred dollars up or down. It can take hundreds of hours before results reliably look like the math. Many counters never earn more than modest sums, and some lose money because of mistakes, bad rules, or an undisciplined bankroll.
Where to go from here
If you’re new, follow this path: first learn the Hi-Lo system, then get the running count to feel automatic. After that, learn the true count, the basics of bet sizing, and finally the realities of casino play and legality.