The Mathematical Basis of Doubling Strategies in Blackjack

June 27, 2014


When it comes to blackjack, players start off learning how to hit and stand and the basic ideas of how to try to get a better hand than the dealer. The next strategic option they learn about is doubling, and learning to double correctly can add a nice chunk of chance eto any player's winrate. There are two ways to learn doubling, and if you plan on playing multiple types of blackjack, one way is drastically better than the other. We want to introduce both of these methods here and show you why understanding the mathematical basis of doubling is superior.

The first method is to just try to memorize all of the times that you're supposed to double using charts and other types of visuals. The problem with this approach is that it doesn't build any understanding of why doubling works or how to figure out when it's the right play on your own. Then when you move to a different type of blackjack, you have to learn a completely new doubling strategy because the rules are different and the correct times to double are different. This is extremely inefficient and doesn't teach you anything substantial about the game.

The second method is to look at the mathematical basis of doubling. When you do this, you can get a better feel for when to double based on the conditions of the hand you have and the game you're playing, and you're much more adaptive when you play this way. There are a few factors that go into whether or not you can double, but the general idea is that you have such a big advantage over the dealer that hitting exactly once would give you a profit. When this happens, you double your average profit by doubling the stakes with this option.

The factors you need to consider when doubling are your total, whether you have a soft or hard total, the card the dealer is showing and any special rules for the type of blackjack you're playing. Having a total of ten or eleven is often enough by itself to double against almost any dealer card, and having a soft total of 13 to 17 against a weak dealer card is often enough to double as well. Outside of that, it comes down to the particulars of the situation and of the game you're playing.