When to Double Down?

HERE'S WHEN YOU SHOULD DOUBLE DOWN IN BLACKJACK

• To double down, you make a second bet equal to your first. You then get one more card – and only one. There’s no second hit after doubling.
• Given a common six-deck game in which dealers hit soft 17, basic strategy tables tell you to double down with hard 11 against any dealer up card; on hard 10 when the dealer has any up card from 2 through 9; or on hard 9 when the dealer shows a 3, 4, 5 or 6.
• If you have a soft hand, where you can’t bust because an Ace being counted as 11 can be counted as 1 instead if you get a bad draw, there are a number of double down opportunities. If you have Ace-2 or Ace-3, double if the dealer has 5 or 6; with Ace-4 or Ace 5, double against 4, 5 or 6; with Ace-6, double against 3, 4, 5 or 6; and with Ace-7, double against 2, 3, 4, 5 or 6.
• In ideal conditions, you’re allowed to double down no matter what your first two cards are. Some casinos restrict doubling to hard hands of 10 or 11 or 9, 10 or 11, with no soft doubling. Should you find such restrictions, the next best play after doubling is to hit all blackjack hands above except Ace-7, where standing is the second-best option.

Whenever basic strategy tables call for land-based or online blackjack players to double down, it’s because players have an advantage. It’s a chance to turn a profitable hand even more profitable.

But not all potential gains are equal. On some hands, doubling down will nearly double the profit you could expect if you hit without doubling. On others, the gain is only a few tenths of a cent per dollar wagered.

Doubling on hard 11 is more profitable than on hard 10, and either is more profitable than hard 9 or the soft double hands. You make your biggest gains when the dealer shows a 5 or 6. 

Here’s an example of just how much more profitable doubling is on some hands than others.

If you have hard 11 and the land-based or live dealer shows a 2, your average profit if you hit is about 24 cents per dollar wagered. If you double down instead, your average profit nearly doubles to 48 cents per dollar of your original wager.

More precise figures depend on your specific cards. If your 11 consists of 6-5, average profits per dollar of your original wager are 24.3 cents when hitting or 48.2 when doubling. If you have 9-2 instead, the profit average is 24.0 cents when hitting or 47.6 cents when doubling.

The double-down profit isn’t quite twice the hit profit because by doubling we pass up the chance to hit again should we draw an Ace. By basic strategy, hard 12 against a 2 his a hitting hand, but every other possible draw when starting with hard 11 gives you a standing hand against a 2.

Now compare that to the soft double situation with Ace-2 against a dealer’s 5. If you hit, your average profit is 13.66 cents per dollar wagered. If you double, you raise that average profit to 13.75 cents per dollar of your original wager.

You gain less than a tenth of a percent per dollar wagered by doubling down instead of hitting.

One big difference is that with Ace-2 against 5, there are many more situations in which you’d like to take a second hit if only you hadn’t traded away that option as part of doubling down.

You’d like to hit again if you draw an Ace to give you soft 14, a 2 for soft 14, 3 for soft 16 or 4 for soft 17. Not being allowed to make the best plays to help your hand limits your gains when doubling down.

Still, your average profit is higher when you double than when you don’t, so the basic strategy table tells you to double down. Players should understand that the results are more volatile when they double on this hand, that they’ll lose some hands they’d win if allowed to hit again, and that the overall gain by doubling is small.

With that in mind, let’s separate double down hands into tiers, starting with the most profitable:

WHEN TO DOUBLE DOWN IN BLACKJACK

AVERAGE PROFIT 50 CENTS OR MORE PER $1 OF ORIGINAL WAGER

• Hard 11 vs. 6: 34 cents when hitting, 68 cents when doubling.
• Hard 11 vs. 5: 32 cents when hitting, 63 cents when doubling.
• Hard 11 vs. 4: 29 cents when hitting, 58 cents when doubling.
• Hard 10 vs. 6: 29 cents when hitting, 57 cents when doubling.
• Hard 11 vs. 3: 27 cents when hitting, 53 cents when doubling.
• Hard 10 vs. 5: 27 cents when hitting, 53 cents when doubling.

Note that with hard 11, your average profit is more than half your original bet vs. dealer up cards from 6 down through 3, but with hard 10, you reach that level only against dealer 5 and 6.

Your average finishing hand is better when you start with 11 than with 10. With 11, you can complete a 21 with any of the four 10-value cards, whereas you can turn a 10 into 21 only if you draw an Ace.

AVERAGE PROFIT 40 to 50 CENTS PER $1 OF ORIGINAL WAGER

• Hard 11 vs. 2: 24 cents when hitting, 48 cents when doubling.
• Hard 10 vs. 4: 24 cents when hitting, 47 cents when doubling.
• Hard 11 vs. 7: 29 cents when hitting, 47 cents when doubling.
• Hard 11 vs. 6: 34 cents when hitting, 68 cents when doubling.
• Hard 10 vs. 3: 21 cents when hitting, 42 cents when doubling.
• Hard 10 vs. 7: 26 cents when hitting, 40 cents when doubling.

At this level, we’re still dealing strictly with doubles on hard 11 and 10. Doubles on those hands against 7 are the most profitable plays available in which the dealer can make a doubling hand of 17 or better without hitting.

AVERAGE PROFIT 30 to 40 CENTS PER $1 OF ORIGINAL WAGER

• Hard 10 vs. 2: 19 cents when hitting, 38 cents when doubling.
• Soft 18 vs. 6: 22 cents when standing, 36 cents when doubling.
• Hard 11 vs. 8: 23 cents when hitting, 35 cents when doubling.
• Hard 9 vs. 6: 19 cents when hitting, 31 cents when doubling.
• Soft 18 vs. 5: 20 cents when standing, 30 cents when doubling.

In the 30-40 cent range we see the first soft doubling hands and the best-paying of the doubles on hard 9. 

AVERAGE PROFIT 20 to 30 CENTS PER $1 OF ORIGINAL WAGER

• Hard 10 vs. 8: 20 cents when hitting, 29 cents when doubling.
• Hard 9 vs. 5: 17 cents when hitting, 26 cents when doubling.
• Soft 17 vs. 6: 13 cents when hitting, 25 cents when doubling.
• Soft 18 vs. 4: 17 cents when standing, 25 cents when doubling.
• Hard 11 vs. 9: 16 cents when hitting, 23 cents when doubling.
• Soft 13 vs. 6: 17 cents when hitting, 20 cents when doubling.
• Soft 14 vs. 6: 15 cents when hitting, 20 cents when doubling.
• Soft 15 vs. 6: 15 cents when hitting, 20 cents when doubling.
• Soft 16 vs. 6: 11 cents when hitting, 20 cents when doubling.

From here on out, soft doubles dominate the list. The best, most profitable double downs are the hard totals listed early, and soft doubles bring less profit and more iffy draws.

AVERAGE PROFIT LESS THAN 20 CENTS PER $1 OF ORIGINAL WAGER

• Hard 9 vs. 4: 13 cents when hitting, 19 cents when doubling
• Soft 17 vs. 5: 10 cents when hitting, 19 cents when doubling.
• Hard 11 vs. 10: 12 cents when hitting, 18 cents when doubling.
• Soft 18 vs. 3: 14 cents when standing, 18 cents when doubling.
• Hard 10 vs. 9: 12 cents when hitting, 15 cents when doubling.
• Soft 14 vs. 5: 12 cents when hitting, 14 cents when doubling.
• Soft 13 vs. 5: 13.66 cents when hitting, 13.75 cents when doubling.
• Hard 9 vs. 3: 10 cents when hitting, 13 cents when doubling.
• Soft 16 vs. 5: 8 cents when hitting, 13 cents when doubling.
• Hard 11 vs. Ace: 11 cents when hitting, 12 cents when doubling.
• Soft 15 vs. 5: 9 cents when hitting, 13 cents when doubling.
• Soft 18 vs. 2: 11 cents when standing, 12 cents when doubling.
• Soft 17 vs. 4: Average profit 6 cents when hitting, 12 cents when doubling.
• Soft 17 vs. 3: Average profit 3 cents when hitting, 6 cents when doubling.
• Soft 16 vs. 4: Average profit 4 cents when hitting, 6 cents when doubling.
• Soft 15 vs. 4: Average profit 6.1 cents when hitting, 6.4 cents when doubling.

Note how many of these plays bring marginal gains, such as the gain of three-tenths of a cent when doubling on soft 15 vs. 4. 

Every double down listed on the basic strategy table is an opportunity to enhance our profits, but the opportunities with hard 11 and 10 against weak dealer cards are much greater than the rest.

First published on: 15/1/2019