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Card counting in blackjack: how it works and why it's pointless in online casinos
In the movies, a player with a good memory beats the casino at blackjack again and again. In practice, the point of counting cards online is far from obvious — and here's why.
The movies love a neat storyline: a player with a fine grasp of math, a good memory, and the ability to add up quickly in their head beats the casino at blackjack over and over with ease. In practice, the point of counting cards is nowhere near that obvious.
How card counting works
First off, card counting isn't an exercise reserved for geniuses: a player doesn't need to memorize exact cards, they just try to keep a running balance of the high and low cards still left in the deck. Here's the gist in a few points.
Cards played in previous hands go to the discard tray and don't take part in the next hand until the dealer shuffles them back in with the rest of the deck. A card counter starts with modest bets and watches for a while, paying attention to the cards that have gone to the discards.
If a lot of low cards have been discarded, the share of high cards in the deck grows — that's a good moment to raise your bets, since your odds of a blackjack go up. For the dealer, plenty of high cards is the opposite: a problem, because they keep drawing until they reach at least 17 and so are more likely to bust. That's why it doesn't matter which exact card was discarded — the queen of spades or the jack of hearts: you just need to remember that a high one, or a low one, is gone.
How to track discarded cards effortlessly
You don't have to memorize them at all — use the Hi-Lo method, counting points for the cards heading to the discards. The larger the positive running total, the more it makes sense to raise your bets: there's a strong chance of making at least 20 on two cards. If the total is negative, it means low cards dominate the deck — you should step away, or at least keep your bets small.
The Hi-Lo method step by step
- 0
Start from zero
Before a new shoe, your count is zero.
- +1
Cards from 2 to 6
For each card from 2 through 6 inclusive, add 1 point.
- −1
Tens, face cards, and aces
For each card worth 10, or an ace, subtract 1 point.
- 0
Cards from 7 to 9
For cards worth 7 to 9, leave the count unchanged.
How the random number generator kills the point of counting
The whole idea of counting is that the ratio of high to low cards in the deck shifts after each hand, affecting your odds. But RNG blackjack sends cards to the discards only for show: in reality the algorithm starts every hand as if it were the first, with a full set of cards. That's why counting cards in RNG blackjack is pointless.
How live casinos fight card counting
Even though a live casino has a real dealer, the house has no interest in improving a customer's odds there either. The countermeasures against the 'math types' are simple. A plastic cut card is inserted into the middle of the deck in advance: once the dealer reaches it, they know it's time to shuffle the remainder back with the discards, before any clear skew in the ratio can build up. On top of that, a shuffling machine is used, and the dealer places used cards not in a discard tray but straight back with the remaining deck — so every hand starts from a full set of cards.
Online casinos also analyze a customer's behavior patterns, noting when they raise and when they lower their bet, and can ask the dealer to shuffle immediately — or even force the player away from the table.
Takeaway
Card counting really was successful, but first and foremost in the land-based casinos of the last century, when it was relatively new. Modern online casinos worked out countermeasures long ago and rely on technical tools, so you won't outfox the house this way.