When to Double Down in Blackjack

Doubling down is one of the most common variables utilized by players in the game of blackjack. The rules of doubling can vary form one land-based or online casino to the next, according to the specific variant being played.  To double down is to agree to take one additional card and immediately stand on the resulting total. In order to double down, the player is required to double their initial wager.

One of the most common rule sets for doubling down restricts a player to only being able to double when their hand presents a total of 9, 10 or 11. It could be a hard total of 9-11, or a soft total of 19 or 20. A soft total means there is an Ace involved that is being counted as 11. For example, a hand of Ace-9 could be valued at 10 or 20. Then again, it would rarely benefit the player to take an extra card when their total is already 20.

The 9-11 doubling rule certainly seems to be a good one. The player’s most opportune moments for doubling are with such a total, as it offers the highest chance of producing a high hand total of 19, 20 or 21 should a 10 or Face Card be dealt next. It also ensures that the player’s hand cannot bust. But is this rule actually better for the player?

In reality, restricting a player to only doubling on totals of 9-11 is a deficit for the player. It actually increases the house edge by 0.09%. There are other times when doubling could be highly advantageous. According to the most basic blackjack strategy charts, a player should always double with a hard total of 8-11 when the dealer has a 5 or 6 showing, and with a soft total of 13-18 when the dealer shows 4, 5 or 6.

There are additional times where doubling is recommended. A soft total of 17 should be doubled when the dealer is showing 2 or 3, and a soft 18 should be doubled with a 3 in the dealer’s hand. Even a soft total of 19 should be doubled when the dealer shows 6. Not being able to double in these situations reduces the players overall payout expectations.

When the 9-11 rule is not applied, players are generally allowed to double down only on the first two cards dealt to a hand. This means you can double on any total, so long as you have not Hit. While it reduces the number of moments in which a player can double on specific totals, it does allow for hitting on a wider spread of totals when the right opportunity arises. Thus it is still better than the 9-11 doubling rule. Obviously the best rule set would include doubling on any total, and any number of cards.

Other rules applied to doubling may include the following:

• Double down after splitting: lowers house edge by 0.14%
• Double down after splitting Aces: lowers house edge by 0.08%
• Double down surrender: lowers house edge by 0.10%

The Double Down surrender rule allows a player to forfeit their hand and rescue half of the total bet when the result of a double does not turn out to favor the player’s hand. However, this rule cannot be applied if doubling down causes the player’s hand to bust.