How Does Double Down in Blackjack Work?

Most people know that, in blackjack, you can hit or stand – either take another card or stick with the total you have. Most people know about doubling down, too, but if you’re a novice, learning how to double down can be the biggest game-changer of them all.

That’s the purpose of this post – to explain how, when, and why to double down in a blackjack game.

How to Double Down

Why and When Should You Double Down

You double down for the same reason card counters double down – you have an edge, and you want to get more money into action.

What do you mean, you’re thinking. Doesn’t the casino always have an edge in blackjack?

They do, yes, but in any given hand, the house’s edge might be different. And it changes according to how you play that hand.

If that’s not obvious, think about what happens to your expected value when you have a total of 21 on your first two cards compared to you expected value when you have a total of thirteen on your first two cards.

One hand is probably going to beat the dealer. The other hand is probably going to get beat, either by busting or because the dealer gets a higher total.

Here are some hard hands where doubling down makes sense, at least some of the time:

1. 9
2. 10
3. 11

If the dealer has a three, four, five, or six showing, you should double down with a nine. That’s because of two factors:

For one thing, the next card won’t bust you, no matter what. And most of the time, you’re going to wind up with a solid total.

For the other thing, the dealer has a better than 35% probability of busting with any of these hands.

Combine those two factors, and it’s obvious why you’d want to get more money into action in exchange for only taking one more card.

If you have a hard total of ten, that’s even better. You’ll double down against any dealer up card other than a ten or an ace. (Obviously, those are strong cards for the dealer to have, too.)

Finally, if you have a hard total of 11, you should always double down – unless the dealer has an ace showing. (In fact, you’ll NEVER double down if the dealer is showing an ace.) The probability of getting a ten as your next card – giving you the best possible hand – is better than the probability of getting any other single card.

Most casinos allow you to double down on any of these three totals, but they’ll often have restrictions on which other totals you can double down on. When in doubt, ask the dealer. When evaluating blackjack games, always try to go for the games where you have more freedom in your decisions rather than less.

You’ll also often double down on soft totals, but only when the dealer is likely to have a stiff hand. The soft hands you’ll consider doubling down on are soft sixteen, seventeen, or eighteen. (A “soft” hand is one in which you have an ace that might count as one or as eleven.)

But you’ll only double down on one of these soft hands if the dealer has a card lower than six showing. Those are the hands where the dealer is more likely to go bust. (They’re called “stiff hands.”)

Special Situations

What about after a split? Can you double down on your new total?

In most casinos, doubling after a split is NOT allowed. If you can find a casino that allows you to double after splitting, though, the house edge on that game is much better than usual – unless the casino has other rules like 6/5 payouts for blackjack, which more than compensates for that tiny percentage they’re giving up.

You’re never allowed to double down after taking a hit. You’re only allowed to double down on your first two cards. If you COULD double down after hitting, you’d have a big edge over the casino under almost any set of rules – even though the times when it would be the correct play wouldn’t be many.

You also can’t double down on a total of 21. Some people might want to double down when they’re dealt a blackjack, because of their hope that they’d get a card that wouldn’t hurt their hand much.

But you’re better off taking your 3 to 2 payout on the blackjack, anyway.

What You Risk When You Double Down

When you think about how many cards of each value are in the deck, it’s easy to see how many basic strategy decisions make sense. There are more tens in the deck than anything else – sixteen of them, total. That’s still not enough to make it the likeliest next card you’ll get, but a lot of others cards – sevens, eights, or nines – will almost always help your hand when you double down.

The risk you take is that you’ll get a six or lower. In fact, the lower the card you get, the worse it is for you.

Suppose you have a hard total of eleven, and you decide to double down. Almost a third of the time, you’ll get a ten, giving you a total of 21.

But another third of the time, you’ll get a six or lower. A six gives you a total of seventeen, which isn’t awful, but a four or five is awful. You’ll wind up with a total of fifteen or sixteen, which is hardly favorable.

Some conservative players prefer to avoid doubling down because of this, but they’re not thinking clearly. In blackjack, you always want to make the move that gives you the best possible expected return.

And that move is obvious in most situations where you might want to double down.

One More Thing to Avoid

I know I’ve already explained how to add to your bet and signal to the dealer that you want to double down, but I want to leave you with one caveat:

When you put that second bet up there, don’t put it on top of the chips that are already there. Put it next to your original bet.

When you put chips on top of other chips at the table, the casino worries that you might have tampered with the chips.

They want to avoid that, and you want to avoid the appearance of that.