How Blackjack Works (2007)

Counting is always possible, nobody can tell if you're just counting in your head. What's detectable and counterable is the way to get advantage from it: you must make your bet much bigger when the count is favorable. That behavior pattern alone is enough for a casino to choose to toss you - they don't even have to prove that you were counting.

Counting works in general because the player's advantage is concentrated into a small number of possible hands. Almost all of your profit comes from blackjack hands paying 3:2, with a bit more from some particular cases like splitting aces and doubling on 11. For everything else, you lose more hands than you win (the asymmetry is that if player and dealer both bust, dealer still takes your money), and you're just trying to tread water to get to the good stuff. The good stuff all requires aces and tens, and counting is to identify the cases when there are more of those available.

Besides counting, the other way to play blackjack profitably is shuffle tracking. It's possible to watch as aces go into the discard pile and visually track them through the shuffle. When you know an ace is coming up soon (even within a range of the next 20 cards), bet big since even a 5% extra chance of an ace makes the expected value of that hand profitable in your favor. Casinos also know to foil this and will eject you in the same way, for a pattern of suddenly making big bets even if they don't necessarily know or prove you're doing it.

Not an expert but my understanding is that it's only feasible on a small enough scale to eke out tiny profits over the long run, too much success will get you rapidly 86'd.

If anyone reading this is intrigued by games of chance with an available skill edge and is considering learning advantage Blackjack, I'd highly recommend learning Poker instead. You're not playing against the house, you're playing against other players, and the house is not incentivized to clamp down on the edges available (though of course they take a cut of everyone's winnings). And it's an endlessly deep strategic game instead of a mechanistic counting game that advantage Blackjack is, which is to say, it's actually fun.

Here's my story about counting blackjack successfully. It takes place in 2014, at the now-demolished Riviera. At the time, the Riviera was pretty run-down, definitely one of the cheapest places on the Strip. I was in Vegas for the first and only time.

They had single-deck blackjack that had a unique side bet. Basically you could make additional bets that you would get dealt a natural blackjack, with a couple variations like getting an extra payout for suited blackjack.

This side bet was even more amenable to counting than standard BJ. The morning after I saw it, I did a quick simulation and discovered that the odds turned player-friendly if you went a single hand without seeing an ace.

I went down and played it. There was a crowd on Saturday night, and the deck was shuffled basically every hand. No good. Sunday morning I had the table to myself. I bet aggressively, starting with $5 min bets and going to $50 if I went two hands without an ace.

The dealer knew almost immediately that I was counting. He made a few snide remarks, but didn't kick me out. No idea why not. Maybe because the side bets are usually suckers' bets, so that gave me some camouflage.

I had a great run of luck, doing way better than expected. In an hour or so I was up $1500. Along the way I hit a suited BJ for $250. The dealer called over the pit boss, who told him to pay me, and then side eyed me for the rest of the session. I left only because I had to get to my flight.

The cashier's cage gave me a hassle about cashing in brown $500 chips. I guess they rarely got any big winners there.

Overall great experience for me. I'm not at all surprised they closed the casino soon after.

Dealers care because the casino cares, and pays them to care.

Card counters (and advantage players in general) are much less likely to tip well compared to the average gambler. The sort of people who think they're making money on a game also tend to recognize that tips cut into profits.