Number of Decks in Blackjack
Fewer decks, lower house edge
The number of decks in play is one of the biggest rule variables in blackjack. In general, fewer decks is better for the player. Measured against an 8-deck baseline, the house edge changes this way:
| Decks | Change in house edge |
|---|---|
| 1 | -0.48 |
| 2 | -0.19 |
| 4 | -0.06 |
| 6 | -0.02 |
| 8 | baseline |
The baseline game (8 decks, dealer stands on soft 17, 3:2 blackjack, double on any two cards, double after split) has a house edge of 0.43% with perfect play. A single deck with otherwise identical rules gets that to about zero or slightly better for the player. The gain from six to eight decks is so small it hardly matters.
Why fewer decks help
The main reason is blackjack itself. With fewer cards, each card you hold changes the makeup of what is left more than it would in a big shoe, and that tilts the odds slightly toward you getting paid for naturals at 3:2 while the dealer cannot be paid extra. Fewer decks also make your doubles and splits a little more profitable.
It also helps you with stiff hands. With fewer decks, strategy shifts a bit: more doubles, and a few different splits. See the charts for single deck and double deck.
But check the other rules
Casinos know that players prefer fewer decks, so they often pair them with worse rules. Before you choose a single deck table over a shoe, compare the full game:
- 6:5 blackjack adds 1.39, three times what a single deck saves. See 6:5 vs 3:2.
- Dealer hitting soft 17 adds 0.22.
- No double after split adds 0.14.
- Double on 10 and 11 only adds 0.18.
A shoe game with 3:2, S17 and double after split can be a better bet than a single deck table with two or three of those penalties. Add up the whole picture in the rules guide.
Decks and card counting
For counters, fewer decks make the count swing faster, which is useful. But single and double deck games are often dealt with shallow penetration, which reduces the benefit. A 6-deck shoe dealt deeply can be better than a single deck dealt to 50%. See deck penetration and how to count cards.
Which strategy chart to use
Single deck and two decks have their own charts. Four, six and eight decks share one: 6 and 8 deck strategy. Choose the deck count in Settings in the trainer and it will show the right chart.
Common questions
Is single deck always the best game?
No. If it pays 6:5, it is worse than a 6-deck shoe with 3:2.
Does the difference between 6 and 8 decks matter?
Only a little: about 0.02 points of house edge.
Why are there fewer single deck tables?
Casinos prefer shoes because they are faster to run and cost less in edge. When single deck tables exist, they often carry other rule penalties.
How do I know the deck count?
It is usually printed on the table or posted on a sign, and the dealer will tell you.