Is there a flaw in blackjack strategy?

12 April 2015

By John Grochowski

QUESTION: Do you know anything about a supposed flaw in blackjack basic strategy? I’ve been reading an online message board with all kinds of talk about this flaw. They say that the original basic strategy calculations had a flaw, and that other have just copied the strategy and picked up the same flaw for decades. They also say that this flaw costs players money.

ANSWER: It’s simply not true that blackjack basic strategy was calculated once, and that everyone else has copied it ever since. Basic strategy has been calculated and recalculated multiple times starting at square one by different analysts and mathematicians.

If basic strategy for a given set of table rules reduce the house edge to half a percent, that doesn’t mean you’re always going to get back 99.5 percent of your wagers. Sometimes you’re going to have winning sessions, and sometimes you’re going to lose more than half a percent. Over the long haul, the odds of the game will lead to the house keeping about 0.5 percent of the wagers placed by those playing basic strategy.

When your losses exceed that 0.5 percent house edge, it’s not because of any flaw. It’s just normal chance within the odds of the game. The flaw is an urban legend.


QUESTION: You’ve written that you should avoid blackjack games where blackjacks pay 6-5 instead of 3-2. I was at a church casino night, and they set up so that blackjacks paid even money. How much worse is that?

ANSWER: Before getting into the odds of the game, a word about charity nights. Understand that the games are there as a fund-raiser, and they’re not always going to give you the same shot to win as casino games. I’ve been to charity nights that pay 3-2 on blackjacks and had casino-level rules on other games, but I’ve also been to events with even-money payoffs on blackjacks, no free odds in craps, 15 percent rakes on poker and even a triple-zero roulette wheel. My rule of thumb is that if I’m willing to make a contribution to the sponsoring charity, I play, and if not, I don’t.

As for the blackjack house edge, given 3-2 pays as a baseline, a reduction to 6-5 payoffs on blackjack increases the house edge by 1.39 percent. If blackjacks pay only even money, that increases the house edge another 0.88 percent, to a total of 2.27 percent relative to 3-2 payoffs.

I explained this once at a seminar, and one of the attendees told me he didn’t think 1.39 percent was that big a deal. I told him that in blackjack, that’s enormous. It’s larger than the entire house edge on the rest of the game.

Let’s look at a plain vanilla game, the kind you can find at hundreds of casinos in the United States. The rules: Six decks, dealer hits soft 17, you may double down after any first two cards, including after splitting pairs, you can split Aces only once with no resplits, but you can resplit other pairs up to three times for a total of four hands.

Under those rules, the house edge against a basic strategy player is 0.64 percent if blackjacks pay 3-2, 2.0 percent if blackjacks pay 6-5, and 2.9 percent if blackjacks pay even money. That means the house edge on the 6-5 game is more than triple that on the 3-2 game, and the even-money game is nearly five times as tough on players as the 3-2 base.

That makes the even-money payoff game one to play only if you want to make a donation.