By CardCount Academy · Reviewed · 9 min read
Card counting has been public knowledge since 1962, and casinos have had six decades to respond. They have not eliminated it, but they have made it considerably harder than books and films suggest. Understanding the casino's side explains why the same skill is worth something at one table and nothing at the next.
The measures fall into two groups: changes to the game that apply to everyone, and responses aimed at one player.
At a glance
| Measure | What it does | Effect on a counter |
|---|---|---|
| Continuous shuffling machine | Cards return to the shuffler after every round | Counting is pointless |
| Shallow cut card | Shuffle with two or more decks undealt | High counts become rare |
| Blackjack pays 6:5 | Adds about 1.4% to the house edge | Usually more than a count can recover |
| More decks | Count swings more slowly | Wider spread and more patience needed |
| No mid-shoe entry | New players wait for the shuffle | Stops back-counting |
| Bet restrictions | Flat bet, or a capped spread | Removes the source of the edge |
| Preferential shuffle | Dealer shuffles when you raise your bet | Removes the favorable rounds |
Changes to the game
Continuous shuffling machines
A continuous shuffling machine (CSM) holds several decks. After each round the dealer feeds the used cards straight back in, where they are mixed with the rest. There is no discard tray building up and no point at which the remaining cards are meaningfully different from a fresh shoe. The count never gets a chance to develop, so there is nothing to exploit.
Do not confuse a CSM with an ordinary automatic shuffler. A batch shuffler mixes a finished shoe while a second shoe is in play; the game itself is dealt from a normal shoe down to a cut card, and can be counted exactly like a hand-shuffled one. The telltale sign of a CSM is that the dealer returns cards to the machine after every hand.
Penetration
The dealer inserts a plastic cut card into the shuffled shoe; when it comes out, the shoe ends. Placing it further from the back means more cards are never dealt. Because the true count reaches high values mostly when few decks remain, cutting off two decks of six instead of one removes most of the profitable rounds without changing a single printed rule. For a counter, penetration is the most important feature of a game — the rules and house edge guide explains the numbers.
6:5 blackjack
Paying 6:5 instead of 3:2 on a blackjack adds about 1.4 percentage points to the house edge. A counter's average advantage in a good game is around one percent, so a 6:5 table is usually unbeatable in practice. These games became widespread in the 2000s, first on single-deck tables advertised as a throwback, and now on many low-limit shoe games.
More decks
Thorp's original analysis was for a single deck. Casinos moved to multiple decks partly in response. With six or eight decks, each card seen changes the composition less, so the count moves away from zero more slowly and favorable situations are rarer. Counting still works, but it needs a wider bet spread and more hours.
No mid-shoe entry
A sign saying new players may not join until the next shuffle is aimed at back-counters, who watch a table without playing and sit down only when the count turns positive.
Responses aimed at you
How counters are spotted
Counting leaves a recognizable pattern, and none of it requires a camera that reads minds:
- Bets that follow the count. Small bets after a run of high cards, large bets after a run of low ones, repeatedly.
- A big jump in bet size late in the shoe with no win to explain it.
- Departures from basic strategy at telling moments — taking insurance only with a big bet out, standing on 16 against a 10 sometimes, splitting tens.
- Leaving or sitting out when the shoe turns bad.
- Concentration. Watching every card at the table, including other players' hands, without much interest in anything else.
Floor supervisors are trained to notice these, and larger casinos can have surveillance staff count down a shoe alongside a player to see whether the bets track the count. Some also use software that evaluates a player's decisions, and share information about known advantage players.
What happens next
- Attention. A supervisor watches the table, makes a phone call, or starts a friendly conversation that is hard to count through.
- Shuffling up. The dealer is told to shuffle whenever you raise your bet, or to move the cut card forward.
- Flat betting. You are told you may keep playing, but only at one bet size. Without a spread there is no edge.
- A back-off. You are told, usually politely, that your blackjack play is no longer welcome.
- Exclusion. You are asked to leave the property. What a casino is permitted to do varies by jurisdiction; see is card counting illegal?
None of these is a punishment for a crime. Counting with your mind is legal; the casino is declining a bet it does not want.
Online blackjack
Standard online blackjack is software. A random number generator deals each hand from a freshly shuffled virtual shoe, so no card you have seen tells you anything about the next round. Counting has no effect at all. A few games advertise that they deal several rounds before reshuffling; unless the game states this clearly and the rules are otherwise good, assume a reshuffle every hand.
Live-dealer games
Live-dealer blackjack uses real cards on video, which looks countable. In practice the conditions are poor: typically eight decks with the cut card near the middle, so half the shoe is never dealt; a slow game with few hands per hour; and sometimes a continuous shuffler. Many sites also forbid any software assistance in their terms. The combination leaves little or no edge to find, and counting from a screen with an app would be exactly the kind of aid casinos prohibit.
What this means if you are learning
A realistic picture of counting includes all of the above. The skill works under specific conditions — a 3:2 game dealt from a shoe to a reasonable depth, with a spread the casino tolerates — and those conditions have to be found, not assumed. Game selection is as much a part of the craft as keeping the count.
It also means that learning to count is worthwhile for reasons other than income. It teaches how the game really works, makes you immune to bad rules and side bets, and is a satisfying mental skill in its own right. That is the spirit in which this site teaches it: the lessons, drills and simulator use play money only.
Educational content only. Card counting does not guarantee winnings, casinos can limit or refuse play, and laws differ by location. Read the disclaimer and, if gambling stops being fun, our responsible gambling page.
Sources and further reading
- Wizard of Odds — Blackjack Rule Variations
- Don Schlesinger, Blackjack Attack: Playing the Pros' Way (RGE Publishing) — origin of the "Illustrious 18".
- Stanford Wong, Professional Blackjack (Pi Yee Press).
- Ken Uston, Million Dollar Blackjack (1981).