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Definition

Double Down

Also known as Double, Doubling, DD

By Reviewed Editorial policy

In short

Doubling down means doubling your bet in exchange for exactly one more card. It is the main way a blackjack player wins money back from the house, and failing to use it correctly is expensive.

Doubling down doubles your stake and commits you to exactly one more card. You cannot hit again afterwards, whatever you draw.

At the table you place a matching stack of chips beside your original bet, never on top of it, which looks like tampering.

Why it matters so much

Blackjack’s low house edge depends on the player’s favourable options being used. Doubling is the largest of them, worth roughly 1.6% of edge on its own.

A player who never doubles is playing a substantially worse game, and it is one of the most common leaks among casual players, usually from reluctance to increase a bet mid-hand.

When to double

Hard totals

  • 11: double against everything except a dealer ace (and against the ace too, in many rule sets)
  • 10: double against 2 through 9
  • 9: double against 3 through 6

Soft totals

  • A2, A3: double against 5–6
  • A4, A5: double against 4–6
  • A6, A7: double against 3–6

The soft doubles are the ones most often missed. Doubling soft 17 against a 5 feels strange, you are doubling a hand that might get worse, but the dealer’s weakness makes it correct.

Rule variations to check

  • Double on any two cards is best. Some tables restrict doubling to totals of 9, 10 and 11, which costs about 0.09%.
  • Double after split (DAS) allowed is worth about 0.14% in your favour.
  • Doubling for less is permitted at most tables. You may double for less than your original bet. It is almost always wrong. If the hand is worth doubling, it is worth doubling fully.

The discipline problem

Doubling requires putting more money out on a hand you might lose, at exactly the moment it feels risky. That discomfort is why people skip it, and skipping it is why their real house edge is 2% rather than 0.5%.

Common questions

When should I double down?

On 11 against almost anything, on 10 against a dealer 2 to 9, and on 9 against 3 to 6. The soft doubles are the ones most players miss: A2 through A7 all double against various low dealer cards.

Is doubling down worth it?

Yes, it is worth roughly 1.6% of blackjack's edge on its own. Players who never double are playing a substantially worse game, and reluctance to increase a bet mid-hand is one of the most common leaks.

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