When to Double Down in Blackjack
Doubling down puts out a second bet for exactly one more card. It pays when your hand is likely to beat the dealer with a single card, usually because you hold 9, 10 or 11, or because the dealer's upcard is weak. The table shows how much doubling gains over simply hitting or standing.
The short answer
- Double 11 against every upcard. If the dealer stands on soft 17, hit 11 against an ace.
- Double 10 against 2 to 9.
- Double 9 against 3 to 6.
- Never double hard 8 or less.
- Double A,2 and A,3 against a 5 or 6, and A,4 and A,5 against 4 to 6.
- Double A,6 against 3 to 6.
- Double A,7 against 2 to 6. If the dealer stands on soft 17, stand on A,7 against a 2.
- Double A,8 against a 6 only when the dealer hits soft 17. Otherwise stand.
This assumes you may double on any first two cards. See how table rules change it.
What doubling is worth, hand by hand
Each cell is the expected value of doubling minus the expected value of the better of hitting and standing, per $1 of your original bet. Hard 12 and above is left out: doubling it always loses more than hitting or standing.
| Your hand | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | A |
|---|---|---|---|---|---|---|---|---|---|---|
| Hard 8 | −0.18 | −0.14 | −0.11 | −0.07 | −0.03 | −0.27 | −0.39 | −0.51 | −0.50 | −0.57 |
| Hard 9 | −0.01 | +0.02 | +0.05 | +0.08 | +0.12 | −0.07 | −0.12 | −0.25 | −0.31 | −0.33 |
| Hard 10 | +0.18 | +0.20 | +0.23 | +0.26 | +0.28 | +0.14 | +0.09 | +0.03 | −0.03 | −0.07 |
| Hard 11 | +0.23 | +0.26 | +0.28 | +0.31 | +0.33 | +0.17 | +0.12 | +0.07 | +0.06 | 0.00 |
| A,2 | −0.12 | −0.08 | −0.04 | −0.01 | +0.03 | −0.31 | −0.37 | −0.42 | −0.41 | −0.49 |
| A,3 | −0.09 | −0.06 | −0.02 | +0.01 | +0.05 | −0.26 | −0.33 | −0.38 | −0.37 | −0.46 |
| A,4 | −0.07 | −0.03 | 0.00 | +0.03 | +0.07 | −0.22 | −0.29 | −0.34 | −0.34 | −0.42 |
| A,5 | −0.05 | −0.01 | +0.02 | +0.05 | +0.09 | −0.18 | −0.25 | −0.31 | −0.31 | −0.39 |
| A,6 | −0.01 | +0.03 | +0.06 | +0.09 | +0.12 | −0.07 | −0.18 | −0.25 | −0.26 | −0.33 |
| A,7 | 0.00 | +0.04 | +0.07 | +0.10 | +0.13 | −0.18 | −0.14 | −0.19 | −0.20 | −0.26 |
| A,8 | −0.14 | −0.10 | −0.07 | −0.03 | +0.01 | −0.30 | −0.40 | −0.36 | −0.30 | −0.42 |
Figures are in dollars per $1 of your original bet. Doubling is better, worse, close call (within 0.015 either way).
Why 11 against a 10 is still a double
A dealer 10 looks strong, but your 11 has a good chance of becoming 21 or 20 with one card. Doubling is worth +0.18 per $1 of your original bet, against +0.12 for hitting. Over many hands that is 6 cents more per $1.
With 10 against a 10 the order flips: doubling is worth −0.01 and hitting +0.03, so you hit. The extra point on 11 is what makes the difference.
Soft doubles: putting more out with a weak-looking hand
A soft hand cannot bust on the next card, so against a dealer who is likely to bust it can be worth doubling even when the hand itself is weak. Soft 18 (A,7) against a 4 is a strong example: standing is worth +0.17, doubling +0.23. You win more by turning a good hand into a bigger bet while the dealer is at their weakest.
The close calls
These doubles are within 1.5 cents per $1 either way:
- hard 9 against a 2: doubling is worse by 0.013. The chart says hit.
- hard 11 against an ace: doubling is better by 0.001. The chart says double.
- soft 13 (A,2) against a 5: doubling is worse by 0.006. The chart says double.
- soft 14 (A,3) against a 5: doubling is better by 0.015. The chart says double.
- soft 15 (A,4) against a 4: doubling is better by 0.001. The chart says double.
- soft 16 (A,5) against a 3: doubling is worse by 0.015. The chart says hit.
- soft 17 (A,6) against a 2: doubling is worse by 0.007. The chart says hit.
- soft 18 (A,7) against a 2: doubling is better by 0.004. The chart says double.
- soft 19 (A,8) against a 6: doubling is better by 0.008. The chart says double.
Where the chart and this table point different ways, the chart is right for a 4 to 8 deck shoe: it accounts for the cards already dealt, which this infinite-deck table does not. The difference is under a cent per $1.
How table rules change it
- Doubling only on 9 to 11, or 10 to 11: every soft double becomes a hit, except A,7 and A,8, where you stand. The hard doubles you are still allowed stay the same.
- Dealer stands on soft 17: hit 11 against an ace, stand on A,7 against a 2, and stand on A,8 against a 6. See the dealer stands on soft 17 chart.
- No hole card (European rules): hit 11 against a 10 or an ace, because a dealer blackjack would take the doubled bet. See the European no hole card chart.
How these numbers are calculated
The figures come from the same engine as the calculator on this site, using an infinite deck: every card is as likely as in a fresh shoe. Doubling takes exactly one card at twice the stake; hitting is followed by the best play from there on. The dealer hits soft 17 and checks for blackjack first, so the figures apply once the dealer has no blackjack.