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Tips for playing a double-deck blackjack game

By Henry Tamburin


blackjackRecently, I received questions from two different blackjack players that dealt with playing a double-deck game, which I decided to make the topic of my column this month.

The first question came from a basic strategy player who normally plays an eight-deck blackjack game. However, his local casino recently started offering a double-deck game. His question was whether or not he should use the same basic playing strategy.

  • After a few exchanges of emails, I found out that the rules for the eight-deck blackjack game were:
  • Dealer stands on soft 17 (s17)
  • Players could double down on any two cards (DOA) and after pair splitting (DAS)
  • Surrender was not offered

The player also mentioned that the playing rules for the doubledeck game were the same, except the dealer hits soft 17 (h17).

I emailed him the following response.

There are a few strategy changes (seven to be exact) when you switch from playing the above eight-deck game (s17, DOA, DAS) to the double-deck game (h17, DOA, DAS). They include the following:

  • Double down hard 11 against a dealer ace.
  • Double down hard 9 against a dealer deuce.
  • Double down A-3 (soft 14) against a dealer 4.
  • Double down A-7 (soft 18) against a dealer deuce.
  • Double down A-8 (soft 19) against a dealer 6.
  • Split 6-6 against a dealer 7.
  • Split 7-7 against a dealer 8.

Bottom line: If you don’t know what the accurate basic playing strategy is for the game you are playing (be it a double-deck, six-deck, eight-deck, or other game), I would suggest you consult the strategy charts and tables in Chapters 3.2 and 3.3 in my Ultimate Guide to Blackjack (free to read and print at /casinoguides/ blackjack/).

The house edge against a basic strategy player in the eight-deck game is 0.43%. In the two-deck game, the house edge decreases to 0.39%, a slight improvement compared to the eight-deck variety. (This assumes, of course, that you play every hand perfectly, which you would do by following the appropriate basic playing strategy.)

The second question came from a fledgling card counter who asked me what changes he needed to make in his betting when switching from a six-deck to a double-deck game. (Same scenario; his local casino just installed a double-deck game. He uses the Hi-Lo counting system.)

The primary differences in counting a double-deck vs. a six-deck game are twofold:

  1. The running count tends to rise and fall more quickly.
  2. You’ll be playing more hands where you have the edge.

Card counters have to be patient when they play a six-deck game because it often takes several rounds after the shuffle before the count goes sufficiently positive, meaning the edge swings in their favor (and the counter will increase his bets). Sometimes the count will never get positive during the entire six-deck shoe. However, on the bright side, once the count goes positive it tends to stay positive for several rounds allowing the counter to fire away with big bets.

When you play a double-deck game, the count is more volatile. It can quickly go positive after a round or two but just as quickly fall into negative territory. You’ll also be playing more hands where you have the edge so you don’t need as big a bet spread as you would for a six-deck game. (This is why card counters need a bigger bet spread in a six- or eight-deck game; they need to bet a lot more when they have the edge to compensate for the more frequent hands they play where they don’t have the edge.) For example, you’ll need a 1??10 or 1??12 bet spread to get a respectable edge in a six-deck game; however, for a double- deck game, a 1??6 or 1??8 spread often will suffice.

Penetration, or the percentage of cards dealt until the shuffle, is very important in double- deck games. Many casinos instruct their dealers to place the cut card at 50%, meaning that, after one deck is played, the decks are shuffled. A double-deck game with 50% penetration is less profitable for a card counter then a similar game with 60% to 75% penetration (1.2 to 1.5 decks played). Therefore, if you are a card counter, you need to be sure the penetration is greater than 50%.

Here’s another tip that can come in handy when you are counting a double-deck game. Because there are only 104 cards in a double-deck game, just a few extra cards that are put into play before the cards are shuffled can significantly increase your advantage. Therefore, if the count is positive and you know that the next round will be the last one before the shuffle, spread and play two (or three) spots. You’ll be playing more hands where you have the edge in the game while consuming more of the undealt cards, which results in deeper penetration (advantageous for the play of the additional hand or hands). (However, don’t use this ploy at the end of every positive deal, because it will attract too much attention from pit supervisors.)

I play mostly double-deck games with good rules and deep penetration. They have been profitable for me but you must be discreet with your counting, and you should limit your playing sessions to no more than an hour. (For details on how to disguise your card counting skills, see Chapter 10.12 in my Ultimate Guide to Blackjack).


Before you jump in and start playing any double-deck game, make sure you check the rules. For example, some casinos are paying only 6-5 for a blackjack (instead of 3-2). Others don’t allow doubling down after pair splitting (DAS). (These are horrible games that should be avoided.) Play only double-deck games where a blackjack is paid at 3-2, you can double down after pair splitting (DAS), and ideally, the dealer stands on soft 17 (s17). (If the playing rules specify that the dealer must hit soft 17 (h17), that’s acceptable, even though it is not as favorable as an s17 game.)

Henry Tamburin, Ph.D. is the author of the Ultimate Guide to Blackjack (, editor of the Blackjack Insider e-Newsletter (, lead instructor for the Golden Touch Blackjack course, and host of For a free three-month subscription to his blackjack newsletter, go to To receive his free catalog, call 1-888-353-3234 or visit


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