Soft Doubling in Blackjack is Easy with the "Rule of 9"

Most solid blackjack players know when to double down with simple hands like your basic hard 11 or 10, and probably even a hard 9. But what about when you have something like Ace/4 and the dealer has a 3 up? Is that a doubling hand or not? The answer is no.

The fact is, most blackjack players mess up their soft doubling hands. It's the trickiest part of the basic strategy, hands down. That's because some soft hands make a good soft double, and others are strictly for suckers--but which is which? Well, telling the difference is easy if you can just remember the "Rule of 9". That's what we'll go over here today so that you never make a bad soft double again.

But first, understand that as a basic strategy player, the only soft hands you should even consider doubling with are when you have Ace/2 through Ace/7. Let's suppose you do have one of those six hands. Now what?

It depends upon which up-card the dealer shows--that's the final determinant. Against a dealer's deuce up, just forget about any soft doubling down; you'll get burned too often. If she has a 5 or 6 up, she's at her weakest; go ahead and double down with all six hands. But when she shows a 3 or a 4, things get a lot trickier. That's where the Rule of 9 comes in.

What you do with the Rule of 9 is add together the dealer's up-card (be it a 3 or a 4) with your kicker (the side-card next to your Ace). If the two add up to 9 or more, double down. If the sum is less than 9, just hit. Here's an example:

With Joe's hand, if you add the dealer's 3 to his 5, it equals only 8. He should just hit. But with Jenny's hand, the dealer's 3 plus her 6 equals 9. She should double down.

Just remember, to even think about soft doubling, you must have Ace/2 through Ace/7 and the dealer must have a 3, 4, 5 or 6 up. Against a 5 or a 6, you'll always pull the trigger, and against a 3 or a 4, you'll play by the Rule of 9.

Here's a test. How should you play the following soft hands?

1. Double. Your 7 plus the dealer's 3 equals 10. By the Rule of 9, doubling down is your best play.
2. Hit. Your 2 plus the dealer's 4 equals only 6, therefore you should just hit.
3. Double. You should always soft double against a dealer's 5 or 6 when you have Ace/2 through Ace/7.
4. Double. Same reason as #3.
5. Hit. You should never soft double against a deuce (unless you're a card counter or are playing with unusual rules).
6. Hit. You should never soft double against higher than a dealer's 6 up.

Finally, I have a confession to make. The Rule of 9 is not 100% perfect. It's only 94% perfect. That's because Ace/4 against a 4 adds up to only 8, but you're actually about a half percent better off by doubling with it, but the rule of 9 says to just hit. It's a borderline play. Nevertheless, following the rule of 9 to the letter, you'll correctly double down with 17 out of 18 proper soft doubles. If you can also remember to pull the trigger on Ace/4 against a 4, you'll have it totally nailed.

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